diff --git a/core/src/main/java/org/apache/druid/data/input/ColumnsFilter.java b/core/src/main/java/org/apache/druid/data/input/ColumnsFilter.java
new file mode 100644
index 000000000000..b01001f8eec1
--- /dev/null
+++ b/core/src/main/java/org/apache/druid/data/input/ColumnsFilter.java
@@ -0,0 +1,183 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.data.input;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Used by some {@link InputSourceReader} implementations in order to know what columns will need to be read out
+ * of the {@link InputRow} objects they create.
+ *
+ * This is meant to be useful as an optimization: if we're reading from a columnar data format, then when a column
+ * isn't going to be needed, we shouldn't read it.
+ *
+ * @see InputSource#reader accepts objects of this class
+ */
+public abstract class ColumnsFilter
+{
+  /**
+   * Accepts all columns.
+   */
+  public static ColumnsFilter all()
+  {
+    return new ExclusionBased(Collections.emptySet());
+  }
+
+  /**
+   * Accepts a specific list of columns.
+   */
+  public static ColumnsFilter inclusionBased(final Set<String> inclusions)
+  {
+    return new InclusionBased(inclusions);
+  }
+
+
+  /**
+   * Accepts all columns, except those on a specific list.
+   */
+  public static ColumnsFilter exclusionBased(final Set<String> exclusions)
+  {
+    return new ExclusionBased(exclusions);
+  }
+
+  /**
+   * Check if a column should be included or not.
+   */
+  public abstract boolean apply(String column);
+
+  /**
+   * Returns a new filter with a particular column added. The returned filter will return true from {@link #apply}
+   * on this column.
+   */
+  public abstract ColumnsFilter plus(String column);
+
+  public static class InclusionBased extends ColumnsFilter
+  {
+    private final Set<String> inclusions;
+
+    private InclusionBased(Set<String> inclusions)
+    {
+      this.inclusions = inclusions;
+    }
+
+    @Override
+    public boolean apply(String column)
+    {
+      return inclusions.contains(column);
+    }
+
+    @Override
+    public ColumnsFilter plus(String column)
+    {
+      if (inclusions.contains(column)) {
+        return this;
+      } else {
+        final Set<String> copy = new HashSet<>(inclusions);
+        copy.add(column);
+        return new InclusionBased(copy);
+      }
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+      if (this == o) {
+        return true;
+      }
+      if (o == null || getClass() != o.getClass()) {
+        return false;
+      }
+      InclusionBased that = (InclusionBased) o;
+      return Objects.equals(inclusions, that.inclusions);
+    }
+
+    @Override
+    public int hashCode()
+    {
+      return Objects.hash(inclusions);
+    }
+
+    @Override
+    public String toString()
+    {
+      return "ColumnsFilter.InclusionBased{" +
+             "inclusions=" + inclusions +
+             '}';
+    }
+  }
+
+  public static class ExclusionBased extends ColumnsFilter
+  {
+    private final Set<String> exclusions;
+
+    public ExclusionBased(Set<String> exclusions)
+    {
+      this.exclusions = exclusions;
+    }
+
+    @Override
+    public boolean apply(String column)
+    {
+      return !exclusions.contains(column);
+    }
+
+    @Override
+    public ColumnsFilter plus(String column)
+    {
+      if (!exclusions.contains(column)) {
+        return this;
+      } else {
+        final Set<String> copy = new HashSet<>(exclusions);
+        copy.remove(column);
+        return new ExclusionBased(copy);
+      }
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+      if (this == o) {
+        return true;
+      }
+      if (o == null || getClass() != o.getClass()) {
+        return false;
+      }
+      ExclusionBased that = (ExclusionBased) o;
+      return Objects.equals(exclusions, that.exclusions);
+    }
+
+    @Override
+    public int hashCode()
+    {
+      return Objects.hash(exclusions);
+    }
+
+    @Override
+    public String toString()
+    {
+      return "ColumnsFilter.ExclusionBased{" +
+             "exclusions=" + exclusions +
+             '}';
+    }
+  }
+}
diff --git a/core/src/main/java/org/apache/druid/data/input/InputRowSchema.java b/core/src/main/java/org/apache/druid/data/input/InputRowSchema.java
index c908187962e7..227bd3a6d198 100644
--- a/core/src/main/java/org/apache/druid/data/input/InputRowSchema.java
+++ b/core/src/main/java/org/apache/druid/data/input/InputRowSchema.java
@@ -22,8 +22,6 @@
 import org.apache.druid.data.input.impl.DimensionsSpec;
 import org.apache.druid.data.input.impl.TimestampSpec;
 
-import java.util.List;
-
 /**
  * Schema of {@link InputRow}.
  */
@@ -31,13 +29,17 @@ public class InputRowSchema
 {
   private final TimestampSpec timestampSpec;
   private final DimensionsSpec dimensionsSpec;
-  private final List<String> metricNames;
+  private final ColumnsFilter columnsFilter;
 
-  public InputRowSchema(TimestampSpec timestampSpec, DimensionsSpec dimensionsSpec, List<String> metricNames)
+  public InputRowSchema(
+      final TimestampSpec timestampSpec,
+      final DimensionsSpec dimensionsSpec,
+      final ColumnsFilter columnsFilter
+  )
   {
     this.timestampSpec = timestampSpec;
     this.dimensionsSpec = dimensionsSpec;
-    this.metricNames = metricNames;
+    this.columnsFilter = columnsFilter;
   }
 
   public TimestampSpec getTimestampSpec()
@@ -50,8 +52,17 @@ public DimensionsSpec getDimensionsSpec()
     return dimensionsSpec;
   }
 
-  public List<String> getMetricNames()
+  /**
+   * A {@link ColumnsFilter} that can filter down the list of columns that must be read after flattening.
+   *
+   * Logically, Druid applies ingestion spec components in a particular order: first flattenSpec (if any), then
+   * timestampSpec, then transformSpec, and finally dimensionsSpec and metricsSpec.
+   *
+   * If a flattenSpec is provided, this method returns a filter that should be applied after flattening. So, it will
+   * be based on what needs to pass between the flattenSpec and everything beyond it.
+   */
+  public ColumnsFilter getColumnsFilter()
   {
-    return metricNames;
+    return columnsFilter;
   }
 }
diff --git a/core/src/main/java/org/apache/druid/data/input/InputSource.java b/core/src/main/java/org/apache/druid/data/input/InputSource.java
index ba0224e8b0b6..0a3cda250f43 100644
--- a/core/src/main/java/org/apache/druid/data/input/InputSource.java
+++ b/core/src/main/java/org/apache/druid/data/input/InputSource.java
@@ -78,5 +78,9 @@ public interface InputSource
    * @param inputFormat        to parse data. It can be null if {@link #needsFormat()} = true
    * @param temporaryDirectory to store temp data. It will be cleaned up automatically once the task is finished.
    */
-  InputSourceReader reader(InputRowSchema inputRowSchema, @Nullable InputFormat inputFormat, File temporaryDirectory);
+  InputSourceReader reader(
+      InputRowSchema inputRowSchema,
+      @Nullable InputFormat inputFormat,
+      File temporaryDirectory
+  );
 }
diff --git a/core/src/main/java/org/apache/druid/data/input/MapBasedInputRow.java b/core/src/main/java/org/apache/druid/data/input/MapBasedInputRow.java
index 59ab8a55710c..e9117f26911a 100644
--- a/core/src/main/java/org/apache/druid/data/input/MapBasedInputRow.java
+++ b/core/src/main/java/org/apache/druid/data/input/MapBasedInputRow.java
@@ -25,8 +25,10 @@
 
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 /**
+ *
  */
 @PublicApi
 public class MapBasedInputRow extends MapBasedRow implements InputRow
@@ -59,6 +61,28 @@ public List<String> getDimensions()
     return dimensions;
   }
 
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    if (!super.equals(o)) {
+      return false;
+    }
+    MapBasedInputRow that = (MapBasedInputRow) o;
+    return Objects.equals(dimensions, that.dimensions);
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(super.hashCode(), dimensions);
+  }
+
   @Override
   public String toString()
   {
diff --git a/core/src/test/java/org/apache/druid/data/input/FirehoseFactoryToInputSourceAdaptorTest.java b/core/src/test/java/org/apache/druid/data/input/FirehoseFactoryToInputSourceAdaptorTest.java
index bd8cbe1fe755..3def28293272 100644
--- a/core/src/test/java/org/apache/druid/data/input/FirehoseFactoryToInputSourceAdaptorTest.java
+++ b/core/src/test/java/org/apache/druid/data/input/FirehoseFactoryToInputSourceAdaptorTest.java
@@ -37,7 +37,6 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.stream.Stream;
@@ -71,7 +70,7 @@ public void testUnimplementedInputFormat() throws IOException
         new InputRowSchema(
             inputRowParser.getParseSpec().getTimestampSpec(),
             inputRowParser.getParseSpec().getDimensionsSpec(),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         null,
         null
diff --git a/core/src/test/java/org/apache/druid/data/input/impl/ColumnsFilterTest.java b/core/src/test/java/org/apache/druid/data/input/impl/ColumnsFilterTest.java
new file mode 100644
index 000000000000..00faf4ea5324
--- /dev/null
+++ b/core/src/test/java/org/apache/druid/data/input/impl/ColumnsFilterTest.java
@@ -0,0 +1,92 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.data.input.impl;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import nl.jqno.equalsverifier.EqualsVerifier;
+import org.apache.druid.data.input.ColumnsFilter;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class ColumnsFilterTest
+{
+  private static final List<String> COLUMNS = ImmutableList.of("a", "b", "c");
+
+  @Test
+  public void testAll()
+  {
+    Assert.assertEquals(
+        ImmutableList.of("a", "b", "c"),
+        apply(ColumnsFilter.all(), COLUMNS)
+    );
+  }
+
+  @Test
+  public void testInclusionBased()
+  {
+    Assert.assertEquals(
+        ImmutableList.of("b"),
+        apply(ColumnsFilter.inclusionBased(ImmutableSet.of("b")), COLUMNS)
+    );
+  }
+
+  @Test
+  public void testInclusionBasedPlus()
+  {
+    Assert.assertEquals(
+        ColumnsFilter.inclusionBased(ImmutableSet.of("a", "b", "c")),
+        ColumnsFilter.inclusionBased(ImmutableSet.of("b", "c")).plus("a").plus("c")
+    );
+  }
+
+  @Test
+  public void testExclusionBased()
+  {
+    Assert.assertEquals(
+        ImmutableList.of("a", "c"),
+        apply(ColumnsFilter.exclusionBased(ImmutableSet.of("b")), COLUMNS)
+    );
+  }
+
+  @Test
+  public void testExclusionBasedPlus()
+  {
+    Assert.assertEquals(
+        ColumnsFilter.exclusionBased(ImmutableSet.of("b")),
+        ColumnsFilter.exclusionBased(ImmutableSet.of("b", "c")).plus("a").plus("c")
+    );
+  }
+
+  @Test
+  public void testEquals()
+  {
+    EqualsVerifier.forClass(ColumnsFilter.InclusionBased.class).usingGetClass().verify();
+    EqualsVerifier.forClass(ColumnsFilter.ExclusionBased.class).usingGetClass().verify();
+  }
+
+  private List<String> apply(ColumnsFilter columnsFilter, List<String> columns)
+  {
+    return columns.stream().filter(columnsFilter::apply).collect(Collectors.toList());
+  }
+}
diff --git a/core/src/test/java/org/apache/druid/data/input/impl/CsvReaderTest.java b/core/src/test/java/org/apache/druid/data/input/impl/CsvReaderTest.java
index ec942379f3b2..c1faa274845c 100644
--- a/core/src/test/java/org/apache/druid/data/input/impl/CsvReaderTest.java
+++ b/core/src/test/java/org/apache/druid/data/input/impl/CsvReaderTest.java
@@ -23,6 +23,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import org.apache.druid.common.config.NullHandling;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
@@ -37,7 +38,6 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -47,7 +47,7 @@ public class CsvReaderTest
   private static final InputRowSchema INPUT_ROW_SCHEMA = new InputRowSchema(
       new TimestampSpec("ts", "auto", null),
       new DimensionsSpec(DimensionsSpec.getDefaultSchemas(Arrays.asList("ts", "name"))),
-      Collections.emptyList()
+      ColumnsFilter.all()
   );
 
   @BeforeClass
@@ -229,7 +229,7 @@ public void testQuotes() throws IOException
         new InputRowSchema(
             new TimestampSpec("Timestamp", "auto", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("Timestamp"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
diff --git a/core/src/test/java/org/apache/druid/data/input/impl/DelimitedReaderTest.java b/core/src/test/java/org/apache/druid/data/input/impl/DelimitedReaderTest.java
index e590ed566a93..c98d8fff6a85 100644
--- a/core/src/test/java/org/apache/druid/data/input/impl/DelimitedReaderTest.java
+++ b/core/src/test/java/org/apache/druid/data/input/impl/DelimitedReaderTest.java
@@ -22,6 +22,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import org.apache.druid.common.config.NullHandling;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
@@ -35,7 +36,6 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -44,7 +44,7 @@ public class DelimitedReaderTest
   private static final InputRowSchema INPUT_ROW_SCHEMA = new InputRowSchema(
       new TimestampSpec("ts", "auto", null),
       new DimensionsSpec(DimensionsSpec.getDefaultSchemas(Arrays.asList("ts", "name"))),
-      Collections.emptyList()
+      ColumnsFilter.all()
   );
 
   @BeforeClass
diff --git a/core/src/test/java/org/apache/druid/data/input/impl/InputEntityIteratingReaderTest.java b/core/src/test/java/org/apache/druid/data/input/impl/InputEntityIteratingReaderTest.java
index e202d152047a..37b35f149829 100644
--- a/core/src/test/java/org/apache/druid/data/input/impl/InputEntityIteratingReaderTest.java
+++ b/core/src/test/java/org/apache/druid/data/input/impl/InputEntityIteratingReaderTest.java
@@ -21,6 +21,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
 import org.apache.druid.java.util.common.DateTimes;
@@ -37,7 +38,6 @@
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 public class InputEntityIteratingReaderTest
@@ -64,7 +64,7 @@ public void test() throws IOException
             new DimensionsSpec(
                 DimensionsSpec.getDefaultSchemas(ImmutableList.of("time", "name", "score"))
             ),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         new CsvInputFormat(
             ImmutableList.of("time", "name", "score"),
diff --git a/core/src/test/java/org/apache/druid/data/input/impl/JsonLineReaderTest.java b/core/src/test/java/org/apache/druid/data/input/impl/JsonLineReaderTest.java
index 3a400b5456b5..c61ad4921bb7 100644
--- a/core/src/test/java/org/apache/druid/data/input/impl/JsonLineReaderTest.java
+++ b/core/src/test/java/org/apache/druid/data/input/impl/JsonLineReaderTest.java
@@ -21,6 +21,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
@@ -66,7 +67,7 @@ public void testParseRow() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -116,7 +117,7 @@ public void testParseRowWithConditional() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -158,7 +159,7 @@ public void testParseRowKeepNullColumns() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(Collections.emptyList())),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -200,7 +201,7 @@ public void testKeepNullColumnsWithNoNullValues() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(Collections.emptyList())),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -242,7 +243,7 @@ public void testFalseKeepNullColumns() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(Collections.emptyList())),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
diff --git a/core/src/test/java/org/apache/druid/data/input/impl/JsonReaderTest.java b/core/src/test/java/org/apache/druid/data/input/impl/JsonReaderTest.java
index f554034469f0..7ab52a095d51 100644
--- a/core/src/test/java/org/apache/druid/data/input/impl/JsonReaderTest.java
+++ b/core/src/test/java/org/apache/druid/data/input/impl/JsonReaderTest.java
@@ -21,6 +21,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -38,7 +39,6 @@
 import org.junit.rules.ExpectedException;
 
 import java.io.IOException;
-import java.util.Collections;
 
 public class JsonReaderTest
 {
@@ -75,7 +75,7 @@ public void testParseMultipleRows() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -141,7 +141,7 @@ public void testParsePrettyFormatJSON() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -194,7 +194,8 @@ public void testInvalidJSONText() throws IOException
 
     final ByteEntity source = new ByteEntity(
         StringUtils.toUtf8("{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4,\"o\":{\"mg\":1}}"
-                           + "{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4xxx,\"o\":{\"mg\":2}}" //baz property is illegal
+                           + "{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4xxx,\"o\":{\"mg\":2}}"
+                           //baz property is illegal
                            + "{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4,\"o\":{\"mg\":3}}")
     );
 
@@ -202,7 +203,7 @@ public void testInvalidJSONText() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -255,7 +256,7 @@ public void testSampleMultipleRows() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -314,7 +315,8 @@ public void testSamplInvalidJSONText() throws IOException
     //2nd row is ill-formed
     final ByteEntity source = new ByteEntity(
         StringUtils.toUtf8("{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4,\"o\":{\"mg\":1}}"
-                           + "{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4xxx,\"o\":{\"mg\":2}}\n" //value of baz is invalid
+                           + "{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4xxx,\"o\":{\"mg\":2}}\n"
+                           //value of baz is invalid
                            + "{\"timestamp\":\"2019-01-01\",\"bar\":null,\"foo\":\"x\",\"baz\":4,\"o\":{\"mg\":3}}\n")
     );
 
@@ -322,7 +324,7 @@ public void testSamplInvalidJSONText() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -377,7 +379,7 @@ public void testEmptyJSONText() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
@@ -431,7 +433,7 @@ public void testSampleEmptyText() throws IOException
         new InputRowSchema(
             new TimestampSpec("timestamp", "iso", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo"))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         source,
         null
diff --git a/docs/configuration/index.md b/docs/configuration/index.md
index 18c23da6be0c..5a91a772b861 100644
--- a/docs/configuration/index.md
+++ b/docs/configuration/index.md
@@ -1286,6 +1286,7 @@ Additional peon configs include:
 |`druid.indexer.task.gracefulShutdownTimeout`|Wait this long on middleManager restart for restorable tasks to gracefully exit.|PT5M|
 |`druid.indexer.task.hadoopWorkingPath`|Temporary working directory for Hadoop tasks.|`/tmp/druid-indexing`|
 |`druid.indexer.task.restoreTasksOnRestart`|If true, MiddleManagers will attempt to stop tasks gracefully on shutdown and restore them on restart.|false|
+|`druid.indexer.task.ignoreTimestampSpecForDruidInputSource`|If true, tasks using the [Druid input source](../ingestion/native-batch.md#druid-input-source) will ignore the provided timestampSpec, and will use the `__time` column of the input datasource. This option is provided for compatibility with ingestion specs written before Druid 0.22.0.|false|
 |`druid.indexer.server.maxChatRequests`|Maximum number of concurrent requests served by a task's chat handler. Set to 0 to disable limiting.|0|
 
 If the peon is running in remote mode, there must be an Overlord up and running. Peons in remote mode can set the following configurations:
@@ -1350,6 +1351,7 @@ then the value from the configuration below is used:
 |`druid.indexer.task.gracefulShutdownTimeout`|Wait this long on Indexer restart for restorable tasks to gracefully exit.|PT5M|
 |`druid.indexer.task.hadoopWorkingPath`|Temporary working directory for Hadoop tasks.|`/tmp/druid-indexing`|
 |`druid.indexer.task.restoreTasksOnRestart`|If true, the Indexer will attempt to stop tasks gracefully on shutdown and restore them on restart.|false|
+|`druid.indexer.task.ignoreTimestampSpecForDruidInputSource`|If true, tasks using the [Druid input source](../ingestion/native-batch.md#druid-input-source) will ignore the provided timestampSpec, and will use the `__time` column of the input datasource. This option is provided for compatibility with ingestion specs written before Druid 0.22.0.|false|
 |`druid.peon.taskActionClient.retry.minWait`|The minimum retry time to communicate with Overlord.|PT5S|
 |`druid.peon.taskActionClient.retry.maxWait`|The maximum retry time to communicate with Overlord.|PT1M|
 |`druid.peon.taskActionClient.retry.maxRetryCount`|The maximum number of retries to communicate with Overlord.|60|
diff --git a/docs/ingestion/native-batch.md b/docs/ingestion/native-batch.md
index 5032ed1a518c..dece5bf260c4 100644
--- a/docs/ingestion/native-batch.md
+++ b/docs/ingestion/native-batch.md
@@ -1292,60 +1292,82 @@ no `inputFormat` field needs to be specified in the ingestion spec when using th
 |type|This should be "druid".|yes|
 |dataSource|A String defining the Druid datasource to fetch rows from|yes|
 |interval|A String representing an ISO-8601 interval, which defines the time range to fetch the data over.|yes|
-|dimensions|A list of Strings containing the names of dimension columns to select from the Druid datasource. If the list is empty, no dimensions are returned. If null, all dimensions are returned. |no|
-|metrics|The list of Strings containing the names of metric columns to select. If the list is empty, no metrics are returned. If null, all metrics are returned.|no|
 |filter| See [Filters](../querying/filters.md). Only rows that match the filter, if specified, will be returned.|no|
 
-A minimal example DruidInputSource spec is shown below:
+The Druid input source can be used for a variety of purposes, including:
 
-```json
-...
-    "ioConfig": {
-      "type": "index_parallel",
-      "inputSource": {
-        "type": "druid",
-        "dataSource": "wikipedia",
-        "interval": "2013-01-01/2013-01-02"
-      }
-      ...
-    },
-...
-```
+- Creating new datasources that are rolled-up copies of existing datasources.
+- Changing the [partitioning or sorting](index.md#partitioning) of a datasource to improve performance.
+- Updating or removing rows using a [`transformSpec`](index.md#transformspec).
 
-The spec above will read all existing dimension and metric columns from
-the `wikipedia` datasource, including all rows with a timestamp (the `__time` column)
-within the interval `2013-01-01/2013-01-02`.
+When using the Druid input source, the timestamp column shows up as a numeric field named `__time` set to the number
+of milliseconds since the epoch (January 1, 1970 00:00:00 UTC). It is common to use this in the timestampSpec, if you
+want the output timestamp to be equivalent to the input timestamp. In this case, set the timestamp column to `__time`
+and the format to `auto` or `millis`.
 
-A spec that applies a filter and reads a subset of the original datasource's columns is shown below.
+It is OK for the input and output datasources to be the same. In this case, newly generated data will overwrite the
+previous data for the intervals specified in the `granularitySpec`. Generally, if you are going to do this, it is a
+good idea to test out your reindexing by writing to a separate datasource before overwriting your main one.
+Alternatively, if your goals can be satisfied by [compaction](compaction.md), consider that instead as a simpler
+approach.
+
+An example task spec is shown below. It reads from a hypothetical raw datasource `wikipedia_raw` and creates a new
+rolled-up datasource `wikipedia_rollup` by grouping on hour, "countryName", and "page".
 
 ```json
-...
+{
+  "type": "index_parallel",
+  "spec": {
+    "dataSchema": {
+      "dataSource": "wikipedia_rollup",
+      "timestampSpec": {
+        "column": "__time",
+        "format": "millis"
+      },
+      "dimensionsSpec": {
+        "dimensions": [
+          "countryName",
+          "page"
+        ]
+      },
+      "metricsSpec": [
+        {
+          "type": "count",
+          "name": "cnt"
+        }
+      ],
+      "granularitySpec": {
+        "type": "uniform",
+        "queryGranularity": "HOUR",
+        "segmentGranularity": "DAY",
+        "intervals": ["2016-06-27/P1D"],
+        "rollup": true
+      }
+    },
     "ioConfig": {
       "type": "index_parallel",
       "inputSource": {
         "type": "druid",
-        "dataSource": "wikipedia",
-        "interval": "2013-01-01/2013-01-02",
-        "dimensions": [
-          "page",
-          "user"
-        ],
-        "metrics": [
-          "added"
-        ],
-        "filter": {
-          "type": "selector",
-          "dimension": "page",
-          "value": "Druid"
-        }
+        "dataSource": "wikipedia_raw",
+        "interval": "2016-06-27/P1D"
       }
-      ...
     },
-...
+    "tuningConfig": {
+      "type": "index_parallel",
+      "partitionsSpec": {
+        "type": "hashed"
+      },
+      "forceGuaranteedRollup": true,
+      "maxNumConcurrentSubTasks": 1
+    }
+  }
+}
 ```
 
-This spec above will only return the `page`, `user` dimensions and `added` metric.
-Only rows where `page` = `Druid` will be returned.
+> Note: Older versions (0.19 and earlier) did not respect the timestampSpec when using the Druid input source. If you
+> have ingestion specs that rely on this and cannot rewrite them, set
+> [`druid.indexer.task.ignoreTimestampSpecForDruidInputSource`](../configuration/index.md#indexer-general-configuration)
+> to `true` to enable a compatibility mode where the timestampSpec is ignored.
 
 ### SQL Input Source
 
diff --git a/extensions-contrib/aliyun-oss-extensions/src/test/java/org/apache/druid/data/input/aliyun/OssInputSourceTest.java b/extensions-contrib/aliyun-oss-extensions/src/test/java/org/apache/druid/data/input/aliyun/OssInputSourceTest.java
index d38bc6627d98..b7e95402e234 100644
--- a/extensions-contrib/aliyun-oss-extensions/src/test/java/org/apache/druid/data/input/aliyun/OssInputSourceTest.java
+++ b/extensions-contrib/aliyun-oss-extensions/src/test/java/org/apache/druid/data/input/aliyun/OssInputSourceTest.java
@@ -39,6 +39,7 @@
 import com.google.inject.Guice;
 import com.google.inject.Injector;
 import com.google.inject.Provides;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
 import org.apache.druid.data.input.InputSourceReader;
@@ -111,7 +112,8 @@ public class OssInputSourceTest extends InitializedNullHandlingTest
   private static final OssClientConfig CLOUD_CONFIG_PROPERTIES = new OssClientConfig(
       "test.oss-cn.aliyun.com",
       new DefaultPasswordProvider("myKey"),
-      new DefaultPasswordProvider("mySecret"));
+      new DefaultPasswordProvider("mySecret")
+  );
 
   private static final List<CloudObjectLocation> EXPECTED_LOCATION =
       ImmutableList.of(new CloudObjectLocation("foo", "bar/file.csv"));
@@ -454,7 +456,7 @@ public void testReader() throws IOException
     InputRowSchema someSchema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2"))),
-        ImmutableList.of("count")
+        ColumnsFilter.all()
     );
 
     InputSourceReader reader = inputSource.reader(
@@ -497,7 +499,7 @@ public void testCompressedReader() throws IOException
     InputRowSchema someSchema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2"))),
-        ImmutableList.of("count")
+        ColumnsFilter.all()
     );
 
     InputSourceReader reader = inputSource.reader(
diff --git a/extensions-core/avro-extensions/src/test/java/org/apache/druid/data/input/avro/AvroOCFReaderTest.java b/extensions-core/avro-extensions/src/test/java/org/apache/druid/data/input/avro/AvroOCFReaderTest.java
index da586d8ed635..4841483c4e1a 100644
--- a/extensions-core/avro-extensions/src/test/java/org/apache/druid/data/input/avro/AvroOCFReaderTest.java
+++ b/extensions-core/avro-extensions/src/test/java/org/apache/druid/data/input/avro/AvroOCFReaderTest.java
@@ -27,6 +27,7 @@
 import org.apache.avro.generic.GenericRecord;
 import org.apache.druid.data.input.AvroHadoopInputRowParserTest;
 import org.apache.druid.data.input.AvroStreamInputRowParserTest;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -199,10 +200,9 @@ private InputEntityReader createReader(
     final TimestampSpec timestampSpec = new TimestampSpec("timestamp", "auto", null);
     final DimensionsSpec dimensionsSpec = new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of(
         "eventType")));
-    final List<String> metricNames = ImmutableList.of("someLong");
 
     final AvroOCFInputFormat inputFormat = new AvroOCFInputFormat(mapper, null, readerSchema, null);
-    final InputRowSchema schema = new InputRowSchema(timestampSpec, dimensionsSpec, metricNames);
+    final InputRowSchema schema = new InputRowSchema(timestampSpec, dimensionsSpec, ColumnsFilter.all());
     final FileEntity entity = new FileEntity(someAvroFile);
     return inputFormat.createReader(schema, entity, temporaryFolder.newFolder());
   }
diff --git a/extensions-core/google-extensions/src/test/java/org/apache/druid/data/input/google/GoogleCloudStorageInputSourceTest.java b/extensions-core/google-extensions/src/test/java/org/apache/druid/data/input/google/GoogleCloudStorageInputSourceTest.java
index e68a9a44a386..4b42efe0d61c 100644
--- a/extensions-core/google-extensions/src/test/java/org/apache/druid/data/input/google/GoogleCloudStorageInputSourceTest.java
+++ b/extensions-core/google-extensions/src/test/java/org/apache/druid/data/input/google/GoogleCloudStorageInputSourceTest.java
@@ -31,6 +31,7 @@
 import com.google.inject.Guice;
 import com.google.inject.Injector;
 import com.google.inject.Provides;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
 import org.apache.druid.data.input.InputSourceReader;
@@ -226,7 +227,7 @@ public void testReader() throws IOException
     InputRowSchema someSchema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2"))),
-        ImmutableList.of("count")
+        ColumnsFilter.all()
     );
 
     InputSourceReader reader = inputSource.reader(
@@ -269,7 +270,7 @@ public void testCompressedReader() throws IOException
     InputRowSchema someSchema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2"))),
-        ImmutableList.of("count")
+        ColumnsFilter.all()
     );
 
     InputSourceReader reader = inputSource.reader(
diff --git a/extensions-core/hdfs-storage/src/test/java/org/apache/druid/inputsource/hdfs/HdfsInputSourceTest.java b/extensions-core/hdfs-storage/src/test/java/org/apache/druid/inputsource/hdfs/HdfsInputSourceTest.java
index a61a0c6de950..96a99ad6fdfe 100644
--- a/extensions-core/hdfs-storage/src/test/java/org/apache/druid/inputsource/hdfs/HdfsInputSourceTest.java
+++ b/extensions-core/hdfs-storage/src/test/java/org/apache/druid/inputsource/hdfs/HdfsInputSourceTest.java
@@ -24,6 +24,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputFormat;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
@@ -76,7 +77,7 @@ public class HdfsInputSourceTest extends InitializedNullHandlingTest
   private static final InputRowSchema INPUT_ROW_SCHEMA = new InputRowSchema(
       new TimestampSpec(null, null, null),
       DimensionsSpec.EMPTY,
-      Collections.emptyList()
+      ColumnsFilter.all()
   );
   private static final InputFormat INPUT_FORMAT = new CsvInputFormat(
       Arrays.asList(TimestampSpec.DEFAULT_COLUMN, COLUMN),
diff --git a/extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/KafkaIndexTaskTest.java b/extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/KafkaIndexTaskTest.java
index 992bb19b6265..3d9dc1c4242a 100644
--- a/extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/KafkaIndexTaskTest.java
+++ b/extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/KafkaIndexTaskTest.java
@@ -2781,7 +2781,8 @@ private void makeToolboxFactory() throws IOException
         true,
         null,
         null,
-        null
+        null,
+        false
     );
     final TestDerbyConnector derbyConnector = derby.getConnector();
     derbyConnector.createDataSourceTable();
diff --git a/extensions-core/kinesis-indexing-service/src/test/java/org/apache/druid/indexing/kinesis/KinesisIndexTaskTest.java b/extensions-core/kinesis-indexing-service/src/test/java/org/apache/druid/indexing/kinesis/KinesisIndexTaskTest.java
index 302a4a089dac..2fe4d333d495 100644
--- a/extensions-core/kinesis-indexing-service/src/test/java/org/apache/druid/indexing/kinesis/KinesisIndexTaskTest.java
+++ b/extensions-core/kinesis-indexing-service/src/test/java/org/apache/druid/indexing/kinesis/KinesisIndexTaskTest.java
@@ -2867,7 +2867,8 @@ private void makeToolboxFactory() throws IOException
         true,
         null,
         null,
-        null
+        null,
+        false
     );
     final TestDerbyConnector derbyConnector = derby.getConnector();
     derbyConnector.createDataSourceTable();
diff --git a/extensions-core/orc-extensions/src/test/java/org/apache/druid/data/input/orc/OrcReaderTest.java b/extensions-core/orc-extensions/src/test/java/org/apache/druid/data/input/orc/OrcReaderTest.java
index bef9b64728f4..9726c0e14671 100644
--- a/extensions-core/orc-extensions/src/test/java/org/apache/druid/data/input/orc/OrcReaderTest.java
+++ b/extensions-core/orc-extensions/src/test/java/org/apache/druid/data/input/orc/OrcReaderTest.java
@@ -21,6 +21,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputFormat;
 import org.apache.druid.data.input.InputRow;
@@ -259,7 +260,7 @@ private InputEntityReader createReader(
       String dataFile
   ) throws IOException
   {
-    final InputRowSchema schema = new InputRowSchema(timestampSpec, dimensionsSpec, Collections.emptyList());
+    final InputRowSchema schema = new InputRowSchema(timestampSpec, dimensionsSpec, ColumnsFilter.all());
     final FileEntity entity = new FileEntity(new File(dataFile));
     return inputFormat.createReader(schema, entity, temporaryFolder.newFolder());
   }
diff --git a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/CompatParquetReaderTest.java b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/CompatParquetReaderTest.java
index f8b586bec67d..60173212b53c 100644
--- a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/CompatParquetReaderTest.java
+++ b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/CompatParquetReaderTest.java
@@ -20,6 +20,7 @@
 package org.apache.druid.data.input.parquet;
 
 import com.google.common.collect.ImmutableList;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -34,7 +35,6 @@
 import org.junit.Test;
 
 import java.io.IOException;
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -49,7 +49,7 @@ public void testBinaryAsString() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("ts", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("field"))),
-        ImmutableList.of()
+        ColumnsFilter.all()
     );
     InputEntityReader reader = createReader(
         file,
@@ -114,7 +114,7 @@ public void testParquet1217() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        ImmutableList.of("metric1")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "col", "col"),
@@ -200,7 +200,7 @@ required group nestedIntsColumn (LIST) {
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.PATH, "extractByLogicalMap", "$.intToStringColumn.1"),
@@ -315,7 +315,7 @@ public void testOldRepeatedInt() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("repeatedInt"))),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "repeatedInt", "repeatedInt")
@@ -353,7 +353,7 @@ public void testReadNestedArrayStruct() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("i32_dec", "extracted1", "extracted2"))),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.PATH, "extracted1", "$.myComplex[0].id"),
@@ -395,7 +395,7 @@ public void testProtoStructWithArray() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.PATH, "extractedOptional", "$.optionalMessage.someId"),
diff --git a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/DecimalParquetReaderTest.java b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/DecimalParquetReaderTest.java
index 50b9fe2df27d..faa80e6d73f3 100644
--- a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/DecimalParquetReaderTest.java
+++ b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/DecimalParquetReaderTest.java
@@ -20,6 +20,7 @@
 package org.apache.druid.data.input.parquet;
 
 import com.google.common.collect.ImmutableList;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -49,7 +50,7 @@ public void testReadParquetDecimalFixedLen() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("fixed_len_dec"))),
-        ImmutableList.of("metric1")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "fixed_len_dec", "fixed_len_dec"),
@@ -86,7 +87,7 @@ public void testReadParquetDecimali32() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("i32_dec"))),
-        ImmutableList.of("metric1")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "i32_dec", "i32_dec"),
@@ -123,7 +124,7 @@ public void testReadParquetDecimali64() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", DateTimes.of("2018-09-01T00:00:00.000Z")),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("i64_dec"))),
-        ImmutableList.of("metric1")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "i32_dec", "i64_dec"),
diff --git a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/FlattenSpecParquetReaderTest.java b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/FlattenSpecParquetReaderTest.java
index 5be38dda494d..7ff430667fa5 100644
--- a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/FlattenSpecParquetReaderTest.java
+++ b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/FlattenSpecParquetReaderTest.java
@@ -20,6 +20,7 @@
 package org.apache.druid.data.input.parquet;
 
 import com.google.common.collect.ImmutableList;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -33,7 +34,6 @@
 import org.junit.Test;
 
 import java.io.IOException;
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -69,7 +69,7 @@ public void testFlat1NoFlattenSpec() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2", "dim3", "listDim"))),
-        ImmutableList.of("metric1", "metric2")
+        ColumnsFilter.all()
     );
     JSONPathSpec flattenSpec = new JSONPathSpec(false, ImmutableList.of());
     InputEntityReader reader = createReader(
@@ -103,7 +103,7 @@ public void testFlat1Autodiscover() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        ImmutableList.of("metric1", "metric2")
+        ColumnsFilter.all()
     );
     InputEntityReader reader = createReader(
         file,
@@ -136,7 +136,7 @@ public void testFlat1Flatten() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2", "dim3", "list"))),
-        ImmutableList.of("metric1", "metric2")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "timestamp", null),
@@ -177,7 +177,7 @@ public void testFlat1FlattenSelectListItem() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2", "listExtracted"))),
-        ImmutableList.of("metric1", "metric2")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "timestamp", null),
@@ -217,7 +217,7 @@ public void testNested1NoFlattenSpec() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1"))),
-        ImmutableList.of("metric1")
+        ColumnsFilter.all()
     );
     JSONPathSpec flattenSpec = new JSONPathSpec(false, ImmutableList.of());
     InputEntityReader reader = createReader(
@@ -253,7 +253,7 @@ public void testNested1Autodiscover() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        ImmutableList.of("metric1", "metric2")
+        ColumnsFilter.all()
     );
     InputEntityReader reader = createReader(
         file,
@@ -286,7 +286,7 @@ public void testNested1Flatten() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        ImmutableList.of("metric1", "metric2")
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "timestamp", null),
@@ -329,7 +329,7 @@ public void testNested1FlattenSelectListItem() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     List<JSONPathFieldSpec> flattenExpr = ImmutableList.of(
         new JSONPathFieldSpec(JSONPathFieldType.ROOT, "timestamp", null),
diff --git a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/ParquetReaderResourceLeakTest.java b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/ParquetReaderResourceLeakTest.java
index 251fa344bb73..f8e56b3f2deb 100644
--- a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/ParquetReaderResourceLeakTest.java
+++ b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/ParquetReaderResourceLeakTest.java
@@ -20,6 +20,7 @@
 package org.apache.druid.data.input.parquet;
 
 import com.google.common.collect.ImmutableList;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
@@ -39,7 +40,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.Collections;
 import java.util.Objects;
 
 public class ParquetReaderResourceLeakTest extends BaseParquetReaderTest
@@ -55,7 +55,7 @@ public void testFetchOnReadCleanupAfterExhaustingIterator() throws IOException
         new DimensionsSpec(
             DimensionsSpec.getDefaultSchemas(ImmutableList.of("page", "language", "user", "unpatrolled"))
         ),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     FetchingFileEntity entity = new FetchingFileEntity(new File("example/wiki/wiki.parquet"));
     ParquetInputFormat parquet = new ParquetInputFormat(JSONPathSpec.DEFAULT, false, new Configuration());
diff --git a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/TimestampsParquetReaderTest.java b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/TimestampsParquetReaderTest.java
index 19f1544dcff0..c0189fe8bc19 100644
--- a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/TimestampsParquetReaderTest.java
+++ b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/TimestampsParquetReaderTest.java
@@ -20,6 +20,7 @@
 package org.apache.druid.data.input.parquet;
 
 import com.google.common.collect.ImmutableList;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -31,7 +32,6 @@
 import org.junit.Test;
 
 import java.io.IOException;
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -46,12 +46,12 @@ public void testDateHandling() throws IOException
     InputRowSchema schemaAsString = new InputRowSchema(
         new TimestampSpec("date_as_string", "Y-M-d", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     InputRowSchema schemaAsDate = new InputRowSchema(
         new TimestampSpec("date_as_date", null, null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     InputEntityReader readerAsString = createReader(
         file,
@@ -104,7 +104,7 @@ public void testParseInt96Timestamp() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("ts", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     InputEntityReader reader = createReader(file, schema, JSONPathSpec.DEFAULT);
 
@@ -130,7 +130,7 @@ public void testTimeMillisInInt64() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of())),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     InputEntityReader reader = createReader(
         file,
diff --git a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/WikiParquetReaderTest.java b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/WikiParquetReaderTest.java
index 75e5e916ec78..4bc7bac27b2e 100644
--- a/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/WikiParquetReaderTest.java
+++ b/extensions-core/parquet-extensions/src/test/java/org/apache/druid/data/input/parquet/WikiParquetReaderTest.java
@@ -20,6 +20,7 @@
 package org.apache.druid.data.input.parquet;
 
 import com.google.common.collect.ImmutableList;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -31,7 +32,6 @@
 import org.junit.Test;
 
 import java.io.IOException;
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -45,7 +45,7 @@ public void testWiki() throws IOException
     InputRowSchema schema = new InputRowSchema(
         new TimestampSpec("timestamp", "iso", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("page", "language", "user", "unpatrolled"))),
-        Collections.emptyList()
+        ColumnsFilter.all()
     );
     InputEntityReader reader = createReader("example/wiki/wiki.parquet", schema, JSONPathSpec.DEFAULT);
 
diff --git a/extensions-core/s3-extensions/src/test/java/org/apache/druid/data/input/s3/S3InputSourceTest.java b/extensions-core/s3-extensions/src/test/java/org/apache/druid/data/input/s3/S3InputSourceTest.java
index 9efaf4fd09c3..41a5f8a36c8b 100644
--- a/extensions-core/s3-extensions/src/test/java/org/apache/druid/data/input/s3/S3InputSourceTest.java
+++ b/extensions-core/s3-extensions/src/test/java/org/apache/druid/data/input/s3/S3InputSourceTest.java
@@ -40,6 +40,7 @@
 import com.google.inject.Guice;
 import com.google.inject.Injector;
 import com.google.inject.Provides;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
 import org.apache.druid.data.input.InputSourceReader;
@@ -509,7 +510,7 @@ public void testReader() throws IOException
     InputRowSchema someSchema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2"))),
-        ImmutableList.of("count")
+        ColumnsFilter.all()
     );
 
     InputSourceReader reader = inputSource.reader(
@@ -553,7 +554,7 @@ public void testCompressedReader() throws IOException
     InputRowSchema someSchema = new InputRowSchema(
         new TimestampSpec("time", "auto", null),
         new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("dim1", "dim2"))),
-        ImmutableList.of("count")
+        ColumnsFilter.all()
     );
 
     InputSourceReader reader = inputSource.reader(
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/common/ReingestionTimelineUtils.java b/indexing-service/src/main/java/org/apache/druid/indexing/common/ReingestionTimelineUtils.java
index bd9d21457eb6..8714fa6933ac 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/common/ReingestionTimelineUtils.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/common/ReingestionTimelineUtils.java
@@ -34,6 +34,10 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
+/**
+ * @deprecated only used by {@link org.apache.druid.indexing.firehose.IngestSegmentFirehoseFactory}
+ */
+@Deprecated
 public class ReingestionTimelineUtils
 {
   /**
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/common/config/TaskConfig.java b/indexing-service/src/main/java/org/apache/druid/indexing/common/config/TaskConfig.java
index 7c22dad5b62b..bf887e500e6e 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/common/config/TaskConfig.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/common/config/TaskConfig.java
@@ -67,6 +67,9 @@ public class TaskConfig
   @JsonProperty
   private final List<StorageLocationConfig> shuffleDataLocations;
 
+  @JsonProperty
+  private final boolean ignoreTimestampSpecForDruidInputSource;
+
   @JsonCreator
   public TaskConfig(
       @JsonProperty("baseDir") String baseDir,
@@ -77,7 +80,8 @@ public TaskConfig(
       @JsonProperty("restoreTasksOnRestart") boolean restoreTasksOnRestart,
       @JsonProperty("gracefulShutdownTimeout") Period gracefulShutdownTimeout,
       @JsonProperty("directoryLockTimeout") Period directoryLockTimeout,
-      @JsonProperty("shuffleDataLocations") List<StorageLocationConfig> shuffleDataLocations
+      @JsonProperty("shuffleDataLocations") List<StorageLocationConfig> shuffleDataLocations,
+      @JsonProperty("ignoreTimestampSpecForDruidInputSource") boolean ignoreTimestampSpecForDruidInputSource
   )
   {
     this.baseDir = baseDir == null ? System.getProperty("java.io.tmpdir") : baseDir;
@@ -102,6 +106,7 @@ public TaskConfig(
     } else {
       this.shuffleDataLocations = shuffleDataLocations;
     }
+    this.ignoreTimestampSpecForDruidInputSource = ignoreTimestampSpecForDruidInputSource;
   }
 
   @JsonProperty
@@ -178,6 +183,12 @@ public List<StorageLocationConfig> getShuffleDataLocations()
     return shuffleDataLocations;
   }
 
+  @JsonProperty
+  public boolean isIgnoreTimestampSpecForDruidInputSource()
+  {
+    return ignoreTimestampSpecForDruidInputSource;
+  }
+
   private String defaultDir(@Nullable String configParameter, final String defaultVal)
   {
     if (configParameter == null) {
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/AbstractBatchIndexTask.java b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/AbstractBatchIndexTask.java
index 6f7cdf68cfe6..72f150226644 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/AbstractBatchIndexTask.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/AbstractBatchIndexTask.java
@@ -26,7 +26,6 @@
 import org.apache.druid.data.input.FirehoseFactory;
 import org.apache.druid.data.input.InputFormat;
 import org.apache.druid.data.input.InputRow;
-import org.apache.druid.data.input.InputRowSchema;
 import org.apache.druid.data.input.InputSource;
 import org.apache.druid.data.input.InputSourceReader;
 import org.apache.druid.indexer.TaskStatus;
@@ -42,6 +41,7 @@
 import org.apache.druid.indexing.common.task.IndexTask.IndexTuningConfig;
 import org.apache.druid.indexing.firehose.IngestSegmentFirehoseFactory;
 import org.apache.druid.indexing.firehose.WindowedSegmentId;
+import org.apache.druid.indexing.input.InputRowSchemas;
 import org.apache.druid.indexing.overlord.Segments;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.java.util.common.JodaUtils;
@@ -49,7 +49,6 @@
 import org.apache.druid.java.util.common.granularity.GranularityType;
 import org.apache.druid.java.util.common.granularity.IntervalsByGranularity;
 import org.apache.druid.java.util.common.logger.Logger;
-import org.apache.druid.query.aggregation.AggregatorFactory;
 import org.apache.druid.segment.incremental.ParseExceptionHandler;
 import org.apache.druid.segment.incremental.RowIngestionMeters;
 import org.apache.druid.segment.indexing.DataSchema;
@@ -66,7 +65,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
@@ -176,16 +174,9 @@ public static FilteringCloseableInputRowIterator inputSourceReader(
       ParseExceptionHandler parseExceptionHandler
   ) throws IOException
   {
-    final List<String> metricsNames = Arrays.stream(dataSchema.getAggregators())
-                                            .map(AggregatorFactory::getName)
-                                            .collect(Collectors.toList());
     final InputSourceReader inputSourceReader = dataSchema.getTransformSpec().decorate(
         inputSource.reader(
-            new InputRowSchema(
-                dataSchema.getTimestampSpec(),
-                dataSchema.getDimensionsSpec(),
-                metricsNames
-            ),
+            InputRowSchemas.fromDataSchema(dataSchema),
             inputFormat,
             tmpDir
         )
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CompactionTask.java b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CompactionTask.java
index 8234c351e6ce..6f69811f3e58 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CompactionTask.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/CompactionTask.java
@@ -624,12 +624,13 @@ private static ParallelIndexIOConfig createIoConfig(
             interval,
             null,
             null,
-            dataSchema.getDimensionsSpec().getDimensionNames(),
-            Arrays.stream(dataSchema.getAggregators()).map(AggregatorFactory::getName).collect(Collectors.toList()),
+            null,
+            null,
             toolbox.getIndexIO(),
             coordinatorClient,
             segmentLoaderFactory,
-            retryPolicyFactory
+            retryPolicyFactory,
+            toolbox.getConfig()
         ),
         null,
         false
@@ -699,7 +700,7 @@ private static DataSchema createDataSchema(
     return new
         DataSchema(
         dataSource,
-        new TimestampSpec(null, null, null),
+        new TimestampSpec(ColumnHolder.TIME_COLUMN_NAME, "millis", null),
         finalDimensionsSpec,
         finalMetricsSpec,
         uniformGranularitySpec,
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/InputSourceProcessor.java b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/InputSourceProcessor.java
index 05ac79e733d6..63ebba8daf7c 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/common/task/InputSourceProcessor.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/common/task/InputSourceProcessor.java
@@ -76,6 +76,7 @@ public static SegmentsAndCommitMetadata process(
                                                         ? (DynamicPartitionsSpec) partitionsSpec
                                                         : null;
     final GranularitySpec granularitySpec = dataSchema.getGranularitySpec();
+
     try (
         final CloseableIterator<InputRow> inputRowIterator = AbstractBatchIndexTask.inputSourceReader(
             tmpDir,
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactory.java b/indexing-service/src/main/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactory.java
index 3ba936ebbdaa..01b3d95672e0 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactory.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactory.java
@@ -62,6 +62,10 @@
 import java.util.Map;
 import java.util.stream.Stream;
 
+/**
+ * @deprecated use {@link DruidInputSource} instead
+ */
+@Deprecated
 public class IngestSegmentFirehoseFactory implements FiniteFirehoseFactory<InputRowParser, List<WindowedSegmentId>>
 {
   private static final EmittingLogger log = new EmittingLogger(IngestSegmentFirehoseFactory.class);
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidInputSource.java b/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidInputSource.java
index f10e40b17f46..c9d0f4e464b2 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidInputSource.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidInputSource.java
@@ -22,10 +22,10 @@
 import com.fasterxml.jackson.annotation.JacksonInject;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonInclude;
-import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.FluentIterable;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterators;
 import org.apache.druid.client.coordinator.CoordinatorClient;
 import org.apache.druid.data.input.AbstractInputSource;
@@ -39,10 +39,11 @@
 import org.apache.druid.data.input.SplitHintSpec;
 import org.apache.druid.data.input.impl.InputEntityIteratingReader;
 import org.apache.druid.data.input.impl.SplittableInputSource;
-import org.apache.druid.indexing.common.ReingestionTimelineUtils;
+import org.apache.druid.data.input.impl.TimestampSpec;
 import org.apache.druid.indexing.common.RetryPolicy;
 import org.apache.druid.indexing.common.RetryPolicyFactory;
 import org.apache.druid.indexing.common.SegmentLoaderFactory;
+import org.apache.druid.indexing.common.config.TaskConfig;
 import org.apache.druid.indexing.firehose.WindowedSegmentId;
 import org.apache.druid.java.util.common.IAE;
 import org.apache.druid.java.util.common.ISE;
@@ -50,6 +51,7 @@
 import org.apache.druid.java.util.common.logger.Logger;
 import org.apache.druid.query.filter.DimFilter;
 import org.apache.druid.segment.IndexIO;
+import org.apache.druid.segment.column.ColumnHolder;
 import org.apache.druid.segment.loading.SegmentLoader;
 import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.TimelineObjectHolder;
@@ -70,15 +72,27 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.SortedMap;
 import java.util.TreeMap;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.stream.Stream;
 
+/**
+ * An {@link org.apache.druid.data.input.InputSource} that allows reading from Druid segments.
+ *
+ * Used internally by {@link org.apache.druid.indexing.common.task.CompactionTask}, and can also be used directly.
+ */
+@JsonInclude(JsonInclude.Include.NON_NULL)
 public class DruidInputSource extends AbstractInputSource implements SplittableInputSource<List<WindowedSegmentId>>
 {
   private static final Logger LOG = new Logger(DruidInputSource.class);
 
+  /**
+   * Timestamp formats that the standard __time column can be parsed with.
+   */
+  private static final List<String> STANDARD_TIME_COLUMN_FORMATS = ImmutableList.of("millis", "auto");
+
   /**
    * A Comparator that orders {@link WindowedSegmentId} mainly by segmentId (which is important), and then by intervals
    * (which is arbitrary, and only here for totality of ordering).
@@ -113,12 +127,21 @@ public class DruidInputSource extends AbstractInputSource implements SplittableI
   @Nullable
   private final List<WindowedSegmentId> segmentIds;
   private final DimFilter dimFilter;
-  private final List<String> dimensions;
-  private final List<String> metrics;
   private final IndexIO indexIO;
   private final CoordinatorClient coordinatorClient;
   private final SegmentLoaderFactory segmentLoaderFactory;
   private final RetryPolicyFactory retryPolicyFactory;
+  private final TaskConfig taskConfig;
+
+  /**
+   * Included for serde backwards-compatibility only. Not used.
+   */
+  private final List<String> dimensions;
+
+  /**
+   * Included for serde backwards-compatibility only. Not used.
+   */
+  private final List<String> metrics;
 
   @JsonCreator
   public DruidInputSource(
@@ -133,7 +156,8 @@ public DruidInputSource(
       @JacksonInject IndexIO indexIO,
       @JacksonInject CoordinatorClient coordinatorClient,
       @JacksonInject SegmentLoaderFactory segmentLoaderFactory,
-      @JacksonInject RetryPolicyFactory retryPolicyFactory
+      @JacksonInject RetryPolicyFactory retryPolicyFactory,
+      @JacksonInject TaskConfig taskConfig
   )
   {
     Preconditions.checkNotNull(dataSource, "dataSource");
@@ -150,6 +174,7 @@ public DruidInputSource(
     this.coordinatorClient = Preconditions.checkNotNull(coordinatorClient, "null CoordinatorClient");
     this.segmentLoaderFactory = Preconditions.checkNotNull(segmentLoaderFactory, "null SegmentLoaderFactory");
     this.retryPolicyFactory = Preconditions.checkNotNull(retryPolicyFactory, "null RetryPolicyFactory");
+    this.taskConfig = Preconditions.checkNotNull(taskConfig, "null taskConfig");
   }
 
   @JsonProperty
@@ -167,7 +192,6 @@ public Interval getInterval()
 
   @Nullable
   @JsonProperty("segments")
-  @JsonInclude(Include.NON_NULL)
   public List<WindowedSegmentId> getSegmentIds()
   {
     return segmentIds;
@@ -179,12 +203,18 @@ public DimFilter getDimFilter()
     return dimFilter;
   }
 
+  /**
+   * Included for serde backwards-compatibility only. Not used.
+   */
   @JsonProperty
   public List<String> getDimensions()
   {
     return dimensions;
   }
 
+  /**
+   * Included for serde backwards-compatibility only. Not used.
+   */
   @JsonProperty
   public List<String> getMetrics()
   {
@@ -207,28 +237,38 @@ protected InputSourceReader fixedFormatReader(InputRowSchema inputRowSchema, @Nu
               .from(partitionHolder)
               .transform(chunk -> new DruidSegmentInputEntity(segmentLoader, chunk.getObject(), holder.getInterval()));
         }).iterator();
-    final List<String> effectiveDimensions = ReingestionTimelineUtils.getDimensionsToReingest(
-        dimensions,
-        inputRowSchema.getDimensionsSpec(),
-        timeline
-    );
 
-    List<String> effectiveMetrics;
-    if (metrics == null) {
-      effectiveMetrics = ReingestionTimelineUtils.getUniqueMetrics(timeline);
+    final DruidSegmentInputFormat inputFormat = new DruidSegmentInputFormat(indexIO, dimFilter);
+
+    final InputRowSchema inputRowSchemaToUse;
+
+    if (taskConfig.isIgnoreTimestampSpecForDruidInputSource()) {
+      // Legacy compatibility mode; see https://github.com/apache/druid/pull/10267.
+      LOG.warn("Ignoring the provided timestampSpec and reading the __time column instead. To use timestampSpecs with "
+               + "the 'druid' input source, set druid.indexer.task.ignoreTimestampSpecForDruidInputSource to false.");
+
+      inputRowSchemaToUse = new InputRowSchema(
+          new TimestampSpec(ColumnHolder.TIME_COLUMN_NAME, STANDARD_TIME_COLUMN_FORMATS.iterator().next(), null),
+          inputRowSchema.getDimensionsSpec(),
+          inputRowSchema.getColumnsFilter().plus(ColumnHolder.TIME_COLUMN_NAME)
+      );
     } else {
-      effectiveMetrics = metrics;
+      inputRowSchemaToUse = inputRowSchema;
     }
 
-    final DruidSegmentInputFormat inputFormat = new DruidSegmentInputFormat(
-        indexIO,
-        dimFilter,
-        effectiveDimensions,
-        effectiveMetrics
-    );
+    if (ColumnHolder.TIME_COLUMN_NAME.equals(inputRowSchemaToUse.getTimestampSpec().getTimestampColumn())
+        && !STANDARD_TIME_COLUMN_FORMATS.contains(inputRowSchemaToUse.getTimestampSpec().getTimestampFormat())) {
+      // Slight chance the user did this intentionally, but not likely. Log a warning.
+      LOG.warn(
+          "The provided timestampSpec refers to the %s column without using format %s. If you wanted to read the "
+          + "column as-is, switch formats.",
+          inputRowSchemaToUse.getTimestampSpec().getTimestampColumn(),
+          STANDARD_TIME_COLUMN_FORMATS
+      );
+    }
 
     return new InputEntityIteratingReader(
-        inputRowSchema,
+        inputRowSchemaToUse,
         inputFormat,
         entityIterator,
         temporaryDirectory
@@ -300,7 +340,8 @@ public SplittableInputSource<List<WindowedSegmentId>> withSplit(InputSplit<List<
         indexIO,
         coordinatorClient,
         segmentLoaderFactory,
-        retryPolicyFactory
+        retryPolicyFactory,
+        taskConfig
     );
   }
 
@@ -310,6 +351,43 @@ public boolean needsFormat()
     return false;
   }
 
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    DruidInputSource that = (DruidInputSource) o;
+    return Objects.equals(dataSource, that.dataSource)
+           && Objects.equals(interval, that.interval)
+           && Objects.equals(segmentIds, that.segmentIds)
+           && Objects.equals(dimFilter, that.dimFilter)
+           && Objects.equals(dimensions, that.dimensions)
+           && Objects.equals(metrics, that.metrics);
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(dataSource, interval, segmentIds, dimFilter, dimensions, metrics);
+  }
+
+  @Override
+  public String toString()
+  {
+    return "DruidInputSource{" +
+           "dataSource='" + dataSource + '\'' +
+           ", interval=" + interval +
+           ", segmentIds=" + segmentIds +
+           ", dimFilter=" + dimFilter +
+           (dimensions != null ? ", dimensions=" + dimensions : "") +
+           (metrics != null ? ", metrics=" + metrics : "") +
+           '}';
+  }
+
   public static Iterator<InputSplit<List<WindowedSegmentId>>> createSplits(
       CoordinatorClient coordinatorClient,
       RetryPolicyFactory retryPolicyFactory,
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentInputFormat.java b/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentInputFormat.java
index 80f87721357c..4d028596ff08 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentInputFormat.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentInputFormat.java
@@ -27,26 +27,19 @@
 import org.apache.druid.segment.IndexIO;
 
 import java.io.File;
-import java.util.List;
 
 public class DruidSegmentInputFormat implements InputFormat
 {
   private final IndexIO indexIO;
   private final DimFilter dimFilter;
-  private List<String> dimensions;
-  private List<String> metrics;
 
-  DruidSegmentInputFormat(
+  public DruidSegmentInputFormat(
       IndexIO indexIO,
-      DimFilter dimFilter,
-      List<String> dimensions,
-      List<String> metrics
+      DimFilter dimFilter
   )
   {
     this.indexIO = indexIO;
     this.dimFilter = dimFilter;
-    this.dimensions = dimensions;
-    this.metrics = metrics;
   }
 
   @Override
@@ -65,8 +58,9 @@ public InputEntityReader createReader(
     return new DruidSegmentReader(
         source,
         indexIO,
-        dimensions,
-        metrics,
+        inputRowSchema.getTimestampSpec(),
+        inputRowSchema.getDimensionsSpec(),
+        inputRowSchema.getColumnsFilter(),
         dimFilter,
         temporaryDirectory
     );
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentReader.java b/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentReader.java
index 25ada0a178f8..8e3bfe7108a2 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentReader.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/input/DruidSegmentReader.java
@@ -21,12 +21,18 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
+import com.google.common.base.Supplier;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Sets;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntity;
 import org.apache.druid.data.input.InputEntity.CleanableFile;
 import org.apache.druid.data.input.InputRow;
+import org.apache.druid.data.input.InputRowSchema;
 import org.apache.druid.data.input.IntermediateRowParsingReader;
-import org.apache.druid.data.input.MapBasedInputRow;
-import org.apache.druid.java.util.common.DateTimes;
+import org.apache.druid.data.input.impl.DimensionsSpec;
+import org.apache.druid.data.input.impl.MapInputRowParser;
+import org.apache.druid.data.input.impl.TimestampSpec;
 import org.apache.druid.java.util.common.granularity.Granularities;
 import org.apache.druid.java.util.common.guava.Sequence;
 import org.apache.druid.java.util.common.guava.Sequences;
@@ -35,56 +41,64 @@
 import org.apache.druid.java.util.common.io.Closer;
 import org.apache.druid.java.util.common.parsers.CloseableIterator;
 import org.apache.druid.java.util.common.parsers.ParseException;
-import org.apache.druid.query.dimension.DefaultDimensionSpec;
 import org.apache.druid.query.filter.DimFilter;
+import org.apache.druid.segment.BaseDoubleColumnValueSelector;
+import org.apache.druid.segment.BaseFloatColumnValueSelector;
 import org.apache.druid.segment.BaseLongColumnValueSelector;
 import org.apache.druid.segment.BaseObjectColumnValueSelector;
+import org.apache.druid.segment.ColumnProcessorFactory;
+import org.apache.druid.segment.ColumnProcessors;
 import org.apache.druid.segment.Cursor;
 import org.apache.druid.segment.DimensionSelector;
 import org.apache.druid.segment.IndexIO;
 import org.apache.druid.segment.QueryableIndexStorageAdapter;
 import org.apache.druid.segment.VirtualColumns;
 import org.apache.druid.segment.column.ColumnHolder;
+import org.apache.druid.segment.column.ValueType;
 import org.apache.druid.segment.data.IndexedInts;
 import org.apache.druid.segment.filter.Filters;
 import org.apache.druid.segment.realtime.firehose.WindowedStorageAdapter;
 import org.apache.druid.utils.CollectionUtils;
-import org.joda.time.DateTime;
 
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
+import java.util.Set;
 
 public class DruidSegmentReader extends IntermediateRowParsingReader<Map<String, Object>>
 {
   private final DruidSegmentInputEntity source;
   private final IndexIO indexIO;
-  private final List<String> dimensions;
-  private final List<String> metrics;
+  private final ColumnsFilter columnsFilter;
+  private final InputRowSchema inputRowSchema;
   private final DimFilter dimFilter;
   private final File temporaryDirectory;
 
   DruidSegmentReader(
-      InputEntity source,
-      IndexIO indexIO,
-      List<String> dimensions,
-      List<String> metrics,
-      DimFilter dimFilter,
-      File temporaryDirectory
+      final InputEntity source,
+      final IndexIO indexIO,
+      final TimestampSpec timestampSpec,
+      final DimensionsSpec dimensionsSpec,
+      final ColumnsFilter columnsFilter,
+      final DimFilter dimFilter,
+      final File temporaryDirectory
   )
   {
     Preconditions.checkArgument(source instanceof DruidSegmentInputEntity);
     this.source = (DruidSegmentInputEntity) source;
     this.indexIO = indexIO;
-    this.dimensions = dimensions;
-    this.metrics = metrics;
+    this.columnsFilter = columnsFilter;
+    this.inputRowSchema = new InputRowSchema(
+        timestampSpec,
+        dimensionsSpec,
+        columnsFilter
+    );
     this.dimFilter = dimFilter;
     this.temporaryDirectory = temporaryDirectory;
   }
@@ -109,10 +123,23 @@ protected CloseableIterator<Map<String, Object>> intermediateRowIterator() throw
         null
     );
 
+    // Retain order of columns from the original segments. Useful for preserving dimension order if we're in
+    // schemaless mode.
+    final Set<String> columnsToRead = Sets.newLinkedHashSet(
+        Iterables.filter(
+            Iterables.concat(
+                Collections.singleton(ColumnHolder.TIME_COLUMN_NAME),
+                storageAdapter.getAdapter().getAvailableDimensions(),
+                storageAdapter.getAdapter().getAvailableMetrics()
+            ),
+            columnsFilter::apply
+        )
+    );
+
     final Sequence<Map<String, Object>> sequence = Sequences.concat(
         Sequences.map(
             cursors,
-            this::cursorToSequence
+            cursor -> cursorToSequence(cursor, columnsToRead)
         )
     );
 
@@ -122,8 +149,7 @@ protected CloseableIterator<Map<String, Object>> intermediateRowIterator() throw
   @Override
   protected List<InputRow> parseInputRows(Map<String, Object> intermediateRow) throws ParseException
   {
-    final DateTime timestamp = (DateTime) intermediateRow.get(ColumnHolder.TIME_COLUMN_NAME);
-    return Collections.singletonList(new MapBasedInputRow(timestamp.getMillis(), dimensions, intermediateRow));
+    return Collections.singletonList(MapInputRowParser.parse(inputRowSchema, intermediateRow));
   }
 
   @Override
@@ -137,14 +163,13 @@ protected List<Map<String, Object>> toMap(Map<String, Object> intermediateRow)
    * Map<String, Object> intermediate rows, selecting the dimensions and metrics of this segment reader.
    *
    * @param cursor A cursor
+   *
    * @return A sequence of intermediate rows
    */
-  private Sequence<Map<String, Object>> cursorToSequence(
-      final Cursor cursor
-  )
+  private Sequence<Map<String, Object>> cursorToSequence(final Cursor cursor, final Set<String> columnsToRead)
   {
     return Sequences.simple(
-        () -> new IntermediateRowFromCursorIterator(cursor, dimensions, metrics)
+        () -> new IntermediateRowFromCursorIterator(cursor, columnsToRead)
     );
   }
 
@@ -152,8 +177,9 @@ private Sequence<Map<String, Object>> cursorToSequence(
    * @param sequence    A sequence of intermediate rows generated from a sequence of
    *                    cursors in {@link #intermediateRowIterator()}
    * @param segmentFile The underlying segment file containing the row data
+   *
    * @return A CloseableIterator from a sequence of intermediate rows, closing the underlying segment file
-   *         when the iterator is closed.
+   * when the iterator is closed.
    */
   @VisibleForTesting
   static CloseableIterator<Map<String, Object>> makeCloseableIteratorFromSequenceAndSegmentFile(
@@ -190,6 +216,66 @@ public void close() throws IOException
     };
   }
 
+  /**
+   * Reads columns for {@link IntermediateRowFromCursorIterator}.
+   */
+  private static class IntermediateRowColumnProcessorFactory implements ColumnProcessorFactory<Supplier<Object>>
+  {
+    private static final IntermediateRowColumnProcessorFactory INSTANCE = new IntermediateRowColumnProcessorFactory();
+
+    @Override
+    public ValueType defaultType()
+    {
+      return ValueType.STRING;
+    }
+
+    @Override
+    public Supplier<Object> makeDimensionProcessor(DimensionSelector selector, boolean multiValue)
+    {
+      return () -> {
+        final IndexedInts vals = selector.getRow();
+
+        int valsSize = vals.size();
+        if (valsSize == 1) {
+          return selector.lookupName(vals.get(0));
+        } else if (valsSize > 1) {
+          List<String> dimVals = new ArrayList<>(valsSize);
+          for (int i = 0; i < valsSize; ++i) {
+            dimVals.add(selector.lookupName(vals.get(i)));
+          }
+
+          return dimVals;
+        }
+
+        return null;
+      };
+    }
+
+    @Override
+    public Supplier<Object> makeFloatProcessor(BaseFloatColumnValueSelector selector)
+    {
+      return () -> selector.isNull() ? null : selector.getFloat();
+    }
+
+    @Override
+    public Supplier<Object> makeDoubleProcessor(BaseDoubleColumnValueSelector selector)
+    {
+      return () -> selector.isNull() ? null : selector.getDouble();
+    }
+
+    @Override
+    public Supplier<Object> makeLongProcessor(BaseLongColumnValueSelector selector)
+    {
+      return () -> selector.isNull() ? null : selector.getLong();
+    }
+
+    @Override
+    public Supplier<Object> makeComplexProcessor(BaseObjectColumnValueSelector<?> selector)
+    {
+      return selector::getObject;
+    }
+  }
+
   /**
    * Given a {@link Cursor}, a list of dimension names, and a list of metric names, this iterator
    * returns the rows of the cursor as Map<String, Object> intermediate rows.
@@ -197,39 +283,25 @@ public void close() throws IOException
   private static class IntermediateRowFromCursorIterator implements Iterator<Map<String, Object>>
   {
     private final Cursor cursor;
-    private final BaseLongColumnValueSelector timestampColumnSelector;
-    private final Map<String, DimensionSelector> dimSelectors;
-    private final Map<String, BaseObjectColumnValueSelector> metSelectors;
+    private final Map<String, Supplier<Object>> columnReaders;
 
     public IntermediateRowFromCursorIterator(
-        Cursor cursor,
-        List<String> dimensionNames,
-        List<String> metricNames
+        final Cursor cursor,
+        final Set<String> columnsToRead
     )
     {
       this.cursor = cursor;
+      this.columnReaders = CollectionUtils.newLinkedHashMapWithExpectedSize(columnsToRead.size());
 
-      timestampColumnSelector = cursor
-          .getColumnSelectorFactory()
-          .makeColumnValueSelector(ColumnHolder.TIME_COLUMN_NAME);
-
-      dimSelectors = new HashMap<>();
-      for (String dim : dimensionNames) {
-        final DimensionSelector dimSelector = cursor
-            .getColumnSelectorFactory()
-            .makeDimensionSelector(new DefaultDimensionSpec(dim, dim));
-        // dimSelector is null if the dimension is not present
-        if (dimSelector != null) {
-          dimSelectors.put(dim, dimSelector);
-        }
-      }
-
-      metSelectors = new HashMap<>();
-      for (String metric : metricNames) {
-        final BaseObjectColumnValueSelector metricSelector = cursor
-            .getColumnSelectorFactory()
-            .makeColumnValueSelector(metric);
-        metSelectors.put(metric, metricSelector);
+      for (String column : columnsToRead) {
+        columnReaders.put(
+            column,
+            ColumnProcessors.makeProcessor(
+                column,
+                IntermediateRowColumnProcessorFactory.INSTANCE,
+                cursor.getColumnSelectorFactory()
+            )
+        );
       }
     }
 
@@ -245,46 +317,18 @@ public Map<String, Object> next()
       if (!hasNext()) {
         throw new NoSuchElementException();
       }
-      final Map<String, Object> theEvent =
-          CollectionUtils.newLinkedHashMapWithExpectedSize(dimSelectors.size() + metSelectors.size() + 1);
-
-      for (Entry<String, DimensionSelector> dimSelector : dimSelectors.entrySet()) {
-        final String dim = dimSelector.getKey();
-        final DimensionSelector selector = dimSelector.getValue();
-        final IndexedInts vals = selector.getRow();
-
-        int valsSize = vals.size();
-        if (valsSize == 1) {
-          final String dimVal = selector.lookupName(vals.get(0));
-          theEvent.put(dim, dimVal);
-        } else if (valsSize > 1) {
-          List<String> dimVals = new ArrayList<>(valsSize);
-          for (int i = 0; i < valsSize; ++i) {
-            dimVals.add(selector.lookupName(vals.get(i)));
-          }
-          theEvent.put(dim, dimVals);
-        }
-      }
+      final Map<String, Object> rowMap =
+          CollectionUtils.newLinkedHashMapWithExpectedSize(columnReaders.size());
 
-      for (Entry<String, BaseObjectColumnValueSelector> metSelector : metSelectors.entrySet()) {
-        final String metric = metSelector.getKey();
-        final BaseObjectColumnValueSelector selector = metSelector.getValue();
-        Object value = selector.getObject();
+      for (Entry<String, Supplier<Object>> entry : columnReaders.entrySet()) {
+        final Object value = entry.getValue().get();
         if (value != null) {
-          theEvent.put(metric, value);
+          rowMap.put(entry.getKey(), value);
         }
       }
 
-      // Timestamp is added last because we expect that the time column will always be a date time object.
-      // If it is added earlier, it can be overwritten by metrics or dimenstions with the same name.
-      //
-      // If a user names a metric or dimension `__time` it will be overwritten. This case should be rare since
-      // __time is reserved for the time column in druid segments.
-      final long timestamp = timestampColumnSelector.getLong();
-      theEvent.put(ColumnHolder.TIME_COLUMN_NAME, DateTimes.utc(timestamp));
-
       cursor.advance();
-      return theEvent;
+      return rowMap;
     }
   }
 }
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/input/InputRowSchemas.java b/indexing-service/src/main/java/org/apache/druid/indexing/input/InputRowSchemas.java
new file mode 100644
index 000000000000..f273be7922be
--- /dev/null
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/input/InputRowSchemas.java
@@ -0,0 +1,130 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.input;
+
+import com.google.common.annotations.VisibleForTesting;
+import org.apache.druid.data.input.ColumnsFilter;
+import org.apache.druid.data.input.InputRowSchema;
+import org.apache.druid.data.input.impl.DimensionsSpec;
+import org.apache.druid.data.input.impl.TimestampSpec;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.segment.indexing.DataSchema;
+import org.apache.druid.segment.transform.Transform;
+import org.apache.druid.segment.transform.TransformSpec;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/**
+ * Utilities that are helpful when implementing {@link org.apache.druid.data.input.InputEntityReader}.
+ */
+public class InputRowSchemas
+{
+  private InputRowSchemas()
+  {
+    // No instantiation.
+  }
+
+  /**
+   * Creates an {@link InputRowSchema} from a given {@link DataSchema}.
+   */
+  public static InputRowSchema fromDataSchema(final DataSchema dataSchema)
+  {
+    return new InputRowSchema(
+        dataSchema.getTimestampSpec(),
+        dataSchema.getDimensionsSpec(),
+        createColumnsFilter(
+            dataSchema.getTimestampSpec(),
+            dataSchema.getDimensionsSpec(),
+            dataSchema.getTransformSpec(),
+            dataSchema.getAggregators()
+        )
+    );
+  }
+
+  /**
+   * Build a {@link ColumnsFilter} that can filter down the list of columns that must be read after flattening.
+   *
+   * @see InputRowSchema#getColumnsFilter()
+   */
+  @VisibleForTesting
+  static ColumnsFilter createColumnsFilter(
+      final TimestampSpec timestampSpec,
+      final DimensionsSpec dimensionsSpec,
+      final TransformSpec transformSpec,
+      final AggregatorFactory[] aggregators
+  )
+  {
+    // We'll need to know what fields are generated from transforms, vs. expected from the raw data.
+    final Set<String> transformOutputNames =
+        transformSpec.getTransforms().stream().map(Transform::getName).collect(Collectors.toSet());
+
+    if (dimensionsSpec.hasCustomDimensions()) {
+      // We need an inclusion-based filter.
+      final Set<String> inclusions = new HashSet<>();
+
+      // Add timestamp column.
+      inclusions.add(timestampSpec.getTimestampColumn());
+
+      // Add all transform inputs.
+      inclusions.addAll(transformSpec.getRequiredColumns());
+
+      // Add all dimension inputs that are *not* transform outputs.
+      for (String column : dimensionsSpec.getDimensionNames()) {
+        if (!transformOutputNames.contains(column)) {
+          inclusions.add(column);
+        }
+      }
+
+      // Add all aggregator inputs that are *not* transform outputs.
+      for (AggregatorFactory aggregator : aggregators) {
+        for (String column : aggregator.requiredFields()) {
+          if (!transformOutputNames.contains(column)) {
+            inclusions.add(column);
+          }
+        }
+      }
+
+      return ColumnsFilter.inclusionBased(inclusions);
+    } else {
+      // Schemaless dimensions mode: we need an exclusion-based filter.
+      // Start from the list of dimension exclusions.
+      final Set<String> exclusions = new HashSet<>(dimensionsSpec.getDimensionExclusions());
+
+      // Remove (un-exclude) timestamp column.
+      exclusions.remove(timestampSpec.getTimestampColumn());
+
+      // Remove (un-exclude) all transform inputs.
+      exclusions.removeAll(transformSpec.getRequiredColumns());
+
+      // Remove (un-exclude) all aggregator inputs that are *not* transform outputs.
+      for (AggregatorFactory aggregator : aggregators) {
+        for (String column : aggregator.requiredFields()) {
+          if (!transformOutputNames.contains(column)) {
+            exclusions.remove(column);
+          }
+        }
+      }
+
+      return ColumnsFilter.exclusionBased(exclusions);
+    }
+  }
+}
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/overlord/sampler/InputSourceSampler.java b/indexing-service/src/main/java/org/apache/druid/indexing/overlord/sampler/InputSourceSampler.java
index 4342460813e0..8ff872d50309 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/overlord/sampler/InputSourceSampler.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/overlord/sampler/InputSourceSampler.java
@@ -33,6 +33,7 @@
 import org.apache.druid.data.input.impl.DimensionsSpec;
 import org.apache.druid.data.input.impl.TimedShutoffInputSourceReader;
 import org.apache.druid.data.input.impl.TimestampSpec;
+import org.apache.druid.indexing.input.InputRowSchemas;
 import org.apache.druid.java.util.common.DateTimes;
 import org.apache.druid.java.util.common.FileUtils;
 import org.apache.druid.java.util.common.io.Closer;
@@ -51,8 +52,7 @@
 import javax.annotation.Nullable;
 import java.io.File;
 import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -175,10 +175,10 @@ public SamplerResponse sample(
         columnNames.remove(SamplerInputRow.SAMPLER_ORDERING_COLUMN);
 
         for (Row row : index) {
-          Map<String, Object> parsed = new HashMap<>();
+          Map<String, Object> parsed = new LinkedHashMap<>();
 
-          columnNames.forEach(k -> parsed.put(k, row.getRaw(k)));
           parsed.put(ColumnHolder.TIME_COLUMN_NAME, row.getTimestampFromEpoch());
+          columnNames.forEach(k -> parsed.put(k, row.getRaw(k)));
 
           Number sortKey = row.getMetric(SamplerInputRow.SAMPLER_ORDERING_COLUMN);
           if (sortKey != null) {
@@ -215,14 +215,7 @@ private InputSourceReader buildReader(
       File tempDir
   )
   {
-    final List<String> metricsNames = Arrays.stream(dataSchema.getAggregators())
-                                            .map(AggregatorFactory::getName)
-                                            .collect(Collectors.toList());
-    final InputRowSchema inputRowSchema = new InputRowSchema(
-        dataSchema.getTimestampSpec(),
-        dataSchema.getDimensionsSpec(),
-        metricsNames
-    );
+    final InputRowSchema inputRowSchema = InputRowSchemas.fromDataSchema(dataSchema);
 
     InputSourceReader reader = inputSource.reader(inputRowSchema, inputFormat, tempDir);
 
diff --git a/indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SeekableStreamIndexTaskRunner.java b/indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SeekableStreamIndexTaskRunner.java
index 3bbf7df3f38d..ea8a5ba2ed7f 100644
--- a/indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SeekableStreamIndexTaskRunner.java
+++ b/indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SeekableStreamIndexTaskRunner.java
@@ -61,6 +61,7 @@
 import org.apache.druid.indexing.common.actions.TimeChunkLockAcquireAction;
 import org.apache.druid.indexing.common.task.IndexTaskUtils;
 import org.apache.druid.indexing.common.task.RealtimeIndexTask;
+import org.apache.druid.indexing.input.InputRowSchemas;
 import org.apache.druid.indexing.seekablestream.common.OrderedPartitionableRecord;
 import org.apache.druid.indexing.seekablestream.common.OrderedSequenceNumber;
 import org.apache.druid.indexing.seekablestream.common.RecordSupplier;
@@ -70,7 +71,6 @@
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.java.util.emitter.EmittingLogger;
-import org.apache.druid.query.aggregation.AggregatorFactory;
 import org.apache.druid.segment.incremental.ParseExceptionHandler;
 import org.apache.druid.segment.incremental.RowIngestionMeters;
 import org.apache.druid.segment.indexing.RealtimeIOConfig;
@@ -106,7 +106,6 @@
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -245,13 +244,7 @@ public SeekableStreamIndexTaskRunner(
     this.task = task;
     this.ioConfig = task.getIOConfig();
     this.tuningConfig = task.getTuningConfig();
-    this.inputRowSchema = new InputRowSchema(
-        task.getDataSchema().getTimestampSpec(),
-        task.getDataSchema().getDimensionsSpec(),
-        Arrays.stream(task.getDataSchema().getAggregators())
-              .map(AggregatorFactory::getName)
-              .collect(Collectors.toList())
-    );
+    this.inputRowSchema = InputRowSchemas.fromDataSchema(task.getDataSchema());
     this.inputFormat = ioConfig.getInputFormat();
     this.parser = parser;
     this.authorizerMapper = authorizerMapper;
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/TaskToolboxTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/TaskToolboxTest.java
index 3dc99883998c..ef75df5a52d5 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/TaskToolboxTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/TaskToolboxTest.java
@@ -102,7 +102,7 @@ public void setUp() throws IOException
     EasyMock.replay(task, mockHandoffNotifierFactory);
 
     taskToolbox = new TaskToolboxFactory(
-        new TaskConfig(temporaryFolder.newFile().toString(), null, null, 50000, null, false, null, null, null),
+        new TaskConfig(temporaryFolder.newFile().toString(), null, null, 50000, null, false, null, null, null, false),
         new DruidNode("druid/middlemanager", "localhost", false, 8091, null, true, false),
         mockTaskActionClientFactory,
         mockEmitter,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java
index 08ea6fa0c055..f6b09cbcff84 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java
@@ -1505,7 +1505,18 @@ public SegmentPublishResult announceHistoricalSegments(
     };
 
     taskLockbox = new TaskLockbox(taskStorage, mdc);
-    final TaskConfig taskConfig = new TaskConfig(directory.getPath(), null, null, 50000, null, true, null, null, null);
+    final TaskConfig taskConfig = new TaskConfig(
+        directory.getPath(),
+        null,
+        null,
+        50000,
+        null,
+        true,
+        null,
+        null,
+        null,
+        false
+    );
 
     final TaskActionToolbox taskActionToolbox = new TaskActionToolbox(
         taskLockbox,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskRunTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskRunTest.java
index f3ee50cf42b2..c835397f7bcd 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskRunTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskRunTest.java
@@ -44,6 +44,7 @@
 import org.apache.druid.indexing.common.SegmentLoaderFactory;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.TestUtils;
+import org.apache.druid.indexing.common.config.TaskConfig;
 import org.apache.druid.indexing.common.task.CompactionTask.Builder;
 import org.apache.druid.indexing.common.task.batch.parallel.ParallelIndexTuningConfig;
 import org.apache.druid.indexing.firehose.IngestSegmentFirehoseFactory;
@@ -1188,7 +1189,7 @@ public List<StorageLocationConfig> getLocations()
     );
 
     return new TaskToolbox(
-        null,
+        new TaskConfig(null, null, null, null, null, false, null, null, null, false),
         null,
         createActionClient(task),
         null,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java
index 35b242a0c4ce..4f386abe23d9 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskTest.java
@@ -1479,7 +1479,11 @@ private void assertIngestionSchema(
       final DataSchema dataSchema = ingestionSchema.getDataSchema();
       Assert.assertEquals(DATA_SOURCE, dataSchema.getDataSource());
 
-      Assert.assertEquals(new TimestampSpec(null, null, null), dataSchema.getTimestampSpec());
+      Assert.assertEquals(
+          new TimestampSpec(ColumnHolder.TIME_COLUMN_NAME, "millis", null),
+          dataSchema.getTimestampSpec()
+      );
+
       Assert.assertEquals(
           new HashSet<>(expectedDimensionsSpec.getDimensions()),
           new HashSet<>(dataSchema.getDimensionsSpec().getDimensions())
@@ -1511,11 +1515,6 @@ private void assertIngestionSchema(
       Assert.assertEquals(expectedSegmentIntervals.get(i), druidInputSource.getInterval());
       Assert.assertNull(druidInputSource.getDimFilter());
 
-      Assert.assertEquals(
-          new HashSet<>(expectedDimensionsSpec.getDimensionNames()),
-          new HashSet<>(druidInputSource.getDimensions())
-      );
-
       // assert tuningConfig
       Assert.assertEquals(expectedTuningConfig, ingestionSchema.getTuningConfig());
     }
@@ -1552,7 +1551,7 @@ private static class TestTaskToolbox extends TaskToolbox
     )
     {
       super(
-          null,
+          new TaskConfig(null, null, null, null, null, false, null, null, null, false),
           null,
           taskActionClient,
           null,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/HadoopTaskTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/HadoopTaskTest.java
index 990888e5a96c..caaeea253c73 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/HadoopTaskTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/HadoopTaskTest.java
@@ -116,7 +116,8 @@ public TaskStatus runTask(TaskToolbox toolbox)
         false,
         null,
         null,
-        null
+        null,
+        false
     )).once();
     EasyMock.replay(toolbox);
 
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/IngestionTestBase.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/IngestionTestBase.java
index 3d862a5836a6..6a6aae2b4d4f 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/IngestionTestBase.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/IngestionTestBase.java
@@ -35,6 +35,7 @@
 import org.apache.druid.indexing.common.actions.TaskActionClient;
 import org.apache.druid.indexing.common.actions.TaskActionClientFactory;
 import org.apache.druid.indexing.common.actions.TaskActionToolbox;
+import org.apache.druid.indexing.common.config.TaskConfig;
 import org.apache.druid.indexing.common.config.TaskStorageConfig;
 import org.apache.druid.indexing.overlord.HeapMemoryTaskStorage;
 import org.apache.druid.indexing.overlord.IndexerMetadataStorageCoordinator;
@@ -311,7 +312,7 @@ public ListenableFuture<TaskStatus> run(Task task)
         );
 
         final TaskToolbox box = new TaskToolbox(
-            null,
+            new TaskConfig(null, null, null, null, null, false, null, null, null, false),
             new DruidNode("druid/middlemanager", "localhost", false, 8091, null, true, false),
             taskActionClient,
             null,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RealtimeIndexTaskTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RealtimeIndexTaskTest.java
index 79c0099f509e..5deecafe1f59 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RealtimeIndexTaskTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/RealtimeIndexTaskTest.java
@@ -888,7 +888,18 @@ private TaskToolbox makeToolbox(
       final File directory
   )
   {
-    final TaskConfig taskConfig = new TaskConfig(directory.getPath(), null, null, 50000, null, true, null, null, null);
+    final TaskConfig taskConfig = new TaskConfig(
+        directory.getPath(),
+        null,
+        null,
+        50000,
+        null,
+        true,
+        null,
+        null,
+        null,
+        false
+    );
     final TaskLockbox taskLockbox = new TaskLockbox(taskStorage, mdc);
     try {
       taskStorage.insert(task, TaskStatus.running(task.getId()));
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/AbstractParallelIndexSupervisorTaskTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/AbstractParallelIndexSupervisorTaskTest.java
index f3cd4f523925..86d7ad145838 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/AbstractParallelIndexSupervisorTaskTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/AbstractParallelIndexSupervisorTaskTest.java
@@ -202,7 +202,8 @@ public void setUpAbstractParallelIndexSupervisorTaskTest() throws IOException
             false,
             null,
             null,
-            ImmutableList.of(new StorageLocationConfig(temporaryFolder.newFolder(), null, null))
+            ImmutableList.of(new StorageLocationConfig(temporaryFolder.newFolder(), null, null)),
+            false
         ),
         null
     );
@@ -519,6 +520,8 @@ public Set<DataSegment> getPublishedSegments(Task task)
 
   public void prepareObjectMapper(ObjectMapper objectMapper, IndexIO indexIO)
   {
+    final TaskConfig taskConfig = new TaskConfig(null, null, null, null, null, false, null, null, null, false);
+
     objectMapper.setInjectableValues(
         new InjectableValues.Std()
             .addValue(ExprMacroTable.class, LookupEnabledTestExprMacroTable.INSTANCE)
@@ -535,6 +538,7 @@ public void prepareObjectMapper(ObjectMapper objectMapper, IndexIO indexIO)
             .addValue(CoordinatorClient.class, coordinatorClient)
             .addValue(SegmentLoaderFactory.class, new SegmentLoaderFactory(indexIO, objectMapper))
             .addValue(RetryPolicyFactory.class, new RetryPolicyFactory(new RetryPolicyConfig()))
+            .addValue(TaskConfig.class, taskConfig)
     );
     objectMapper.registerSubtypes(
         new NamedType(ParallelIndexSupervisorTask.class, ParallelIndexSupervisorTask.TYPE),
@@ -550,7 +554,7 @@ public void prepareObjectMapper(ObjectMapper objectMapper, IndexIO indexIO)
   protected TaskToolbox createTaskToolbox(Task task, TaskActionClient actionClient) throws IOException
   {
     return new TaskToolbox(
-        null,
+        new TaskConfig(null, null, null, null, null, false, null, null, null, false),
         new DruidNode("druid/middlemanager", "localhost", false, 8091, null, true, false),
         actionClient,
         null,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidInputSourceTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidInputSourceTest.java
new file mode 100644
index 000000000000..dcdc537e9cd8
--- /dev/null
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidInputSourceTest.java
@@ -0,0 +1,224 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.input;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.InjectableValues;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableList;
+import org.apache.druid.client.coordinator.CoordinatorClient;
+import org.apache.druid.data.input.InputSource;
+import org.apache.druid.guice.IndexingServiceInputSourceModule;
+import org.apache.druid.indexing.common.RetryPolicyFactory;
+import org.apache.druid.indexing.common.SegmentLoaderFactory;
+import org.apache.druid.indexing.common.config.TaskConfig;
+import org.apache.druid.indexing.firehose.WindowedSegmentId;
+import org.apache.druid.java.util.common.Intervals;
+import org.apache.druid.segment.IndexIO;
+import org.apache.druid.segment.TestHelper;
+import org.easymock.EasyMock;
+import org.hamcrest.CoreMatchers;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class DruidInputSourceTest
+{
+  private final IndexIO indexIO = EasyMock.createMock(IndexIO.class);
+  private final CoordinatorClient coordinatorClient = EasyMock.createMock(CoordinatorClient.class);
+  private final SegmentLoaderFactory segmentLoaderFactory = EasyMock.createMock(SegmentLoaderFactory.class);
+  private final RetryPolicyFactory retryPolicyFactory = EasyMock.createMock(RetryPolicyFactory.class);
+  private final TaskConfig taskConfig = EasyMock.createMock(TaskConfig.class);
+
+  private ObjectMapper mapper = null;
+
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  @Before
+  public void setUp()
+  {
+    mapper = TestHelper.makeJsonMapper();
+    mapper.registerModules(new IndexingServiceInputSourceModule().getJacksonModules());
+
+    final InjectableValues.Std injectableValues = (InjectableValues.Std) mapper.getInjectableValues();
+    injectableValues.addValue(IndexIO.class, indexIO);
+    injectableValues.addValue(CoordinatorClient.class, coordinatorClient);
+    injectableValues.addValue(SegmentLoaderFactory.class, segmentLoaderFactory);
+    injectableValues.addValue(RetryPolicyFactory.class, retryPolicyFactory);
+    injectableValues.addValue(TaskConfig.class, taskConfig);
+  }
+
+  @Test
+  public void testSerdeUsingIntervals() throws Exception
+  {
+    final String json = "{"
+                        + "\"type\":\"druid\","
+                        + "\"dataSource\":\"foo\","
+                        + "\"interval\":\"2000-01-01T00:00:00.000Z/2001-01-01T00:00:00.000Z\""
+                        + "}";
+
+    final InputSource inputSource = mapper.readValue(json, InputSource.class);
+
+    Assert.assertThat(inputSource, CoreMatchers.instanceOf(DruidInputSource.class));
+    Assert.assertEquals(
+        new DruidInputSource(
+            "foo",
+            Intervals.of("2000/2001"),
+            null,
+            null,
+            null,
+            null,
+            indexIO,
+            coordinatorClient,
+            segmentLoaderFactory,
+            retryPolicyFactory,
+            taskConfig
+        ),
+        inputSource
+    );
+
+    Assert.assertEquals(json, mapper.writeValueAsString(inputSource));
+  }
+
+  @Test
+  public void testSerdeUsingIntervalsAndLegacyDimensionsMetrics() throws Exception
+  {
+    final String json = "{"
+                        + "\"type\":\"druid\","
+                        + "\"dataSource\":\"foo\","
+                        + "\"interval\":\"2000-01-01T00:00:00.000Z/2001-01-01T00:00:00.000Z\","
+                        + "\"dimensions\":[\"a\"],"
+                        + "\"metrics\":[\"b\"]"
+                        + "}";
+
+    final InputSource inputSource = mapper.readValue(json, InputSource.class);
+
+    Assert.assertThat(inputSource, CoreMatchers.instanceOf(DruidInputSource.class));
+    Assert.assertEquals(
+        new DruidInputSource(
+            "foo",
+            Intervals.of("2000/2001"),
+            null,
+            null,
+            ImmutableList.of("a"),
+            ImmutableList.of("b"),
+            indexIO,
+            coordinatorClient,
+            segmentLoaderFactory,
+            retryPolicyFactory,
+            taskConfig
+        ),
+        inputSource
+    );
+
+    Assert.assertEquals(json, mapper.writeValueAsString(inputSource));
+  }
+
+  @Test
+  public void testSerdeUsingSegments() throws Exception
+  {
+    final String json = "{"
+                        + "\"type\":\"druid\","
+                        + "\"dataSource\":\"foo\","
+                        + "\"segments\":["
+                        + "{\"segmentId\":\"foo_2000-01-01T00:00:00.000Z_2000-01-01T01:00:00.000Z_abc123\","
+                        + "\"intervals\":[\"2000-01-01T00:00:00.000Z/2000-01-01T12:00:00.000Z\"]}"
+                        + "]"
+                        + "}";
+
+    final InputSource inputSource = mapper.readValue(json, InputSource.class);
+
+    Assert.assertThat(inputSource, CoreMatchers.instanceOf(DruidInputSource.class));
+    Assert.assertEquals(
+        new DruidInputSource(
+            "foo",
+            null,
+            ImmutableList.of(
+                new WindowedSegmentId(
+                    "foo_2000-01-01T00:00:00.000Z_2000-01-01T01:00:00.000Z_abc123",
+                    ImmutableList.of(Intervals.of("2000-01-01T00/2000-01-01T12"))
+                )
+            ),
+            null,
+            null,
+            null,
+            indexIO,
+            coordinatorClient,
+            segmentLoaderFactory,
+            retryPolicyFactory,
+            taskConfig
+        ),
+        inputSource
+    );
+
+    Assert.assertEquals(json, mapper.writeValueAsString(inputSource));
+  }
+
+  @Test
+  public void testSerdeUsingBothIntervalsAndSegments() throws Exception
+  {
+    final String json = "{"
+                        + "\"type\":\"druid\","
+                        + "\"dataSource\":\"foo\","
+                        + "\"interval\":\"2000-01-01T00:00:00.000Z/2001-01-01T00:00:00.000Z\","
+                        + "\"segments\":["
+                        + "  {\"segmentId\":\"foo_2000-01-01T00:00:00.000Z_2000-01-01T01:00:00.000Z_abc123\","
+                        + "   \"intervals\":[\"2000-01-01T00:00:00.000Z/2000-01-01T12:00:00.000Z\"]}"
+                        + "]"
+                        + "}";
+
+
+    expectedException.expect(JsonProcessingException.class);
+    expectedException.expectMessage("Specify exactly one of 'interval' and 'segments'");
+
+    mapper.readValue(json, InputSource.class);
+  }
+
+  @Test
+  public void testSerdeUsingNeitherIntervalsNorSegments() throws Exception
+  {
+    final String json = "{"
+                        + "\"type\":\"druid\","
+                        + "\"dataSource\":\"foo\""
+                        + "}";
+
+    expectedException.expect(JsonProcessingException.class);
+    expectedException.expectMessage("Specify exactly one of 'interval' and 'segments'");
+
+    mapper.readValue(json, InputSource.class);
+  }
+
+  @Test
+  public void testSerdeUsingNoDataSource() throws Exception
+  {
+    final String json = "{"
+                        + "\"type\":\"druid\","
+                        + "\"interval\":\"2000-01-01T00:00:00.000Z/2001-01-01T00:00:00.000Z\""
+                        + "}";
+
+    expectedException.expect(JsonProcessingException.class);
+    expectedException.expectMessage("dataSource");
+
+    mapper.readValue(json, InputSource.class);
+  }
+}
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidSegmentReaderTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidSegmentReaderTest.java
index b3f514252256..9270f5f8a573 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidSegmentReaderTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/input/DruidSegmentReaderTest.java
@@ -19,23 +19,528 @@
 
 package org.apache.druid.indexing.input;
 
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import org.apache.commons.lang.mutable.MutableBoolean;
+import org.apache.druid.common.config.NullHandlingTest;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntity.CleanableFile;
+import org.apache.druid.data.input.InputRow;
+import org.apache.druid.data.input.MapBasedInputRow;
+import org.apache.druid.data.input.impl.DimensionsSpec;
+import org.apache.druid.data.input.impl.DoubleDimensionSchema;
+import org.apache.druid.data.input.impl.StringDimensionSchema;
+import org.apache.druid.data.input.impl.TimestampSpec;
+import org.apache.druid.hll.HyperLogLogCollector;
+import org.apache.druid.hll.HyperLogLogHash;
+import org.apache.druid.java.util.common.DateTimes;
+import org.apache.druid.java.util.common.Intervals;
 import org.apache.druid.java.util.common.guava.BaseSequence;
 import org.apache.druid.java.util.common.guava.BaseSequence.IteratorMaker;
 import org.apache.druid.java.util.common.guava.Sequence;
 import org.apache.druid.java.util.common.parsers.CloseableIterator;
+import org.apache.druid.query.aggregation.CountAggregatorFactory;
+import org.apache.druid.query.aggregation.hyperloglog.HyperUniquesAggregatorFactory;
+import org.apache.druid.query.filter.SelectorDimFilter;
+import org.apache.druid.segment.IndexBuilder;
+import org.apache.druid.segment.IndexIO;
+import org.apache.druid.segment.IndexSpec;
+import org.apache.druid.segment.Segment;
+import org.apache.druid.segment.SegmentLazyLoadFailCallback;
+import org.apache.druid.segment.TestHelper;
+import org.apache.druid.segment.incremental.IncrementalIndex;
+import org.apache.druid.segment.incremental.IncrementalIndexSchema;
+import org.apache.druid.segment.loading.SegmentLoader;
+import org.apache.druid.segment.writeout.OnHeapMemorySegmentWriteOutMediumFactory;
+import org.apache.druid.timeline.DataSegment;
+import org.joda.time.Interval;
 import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 
-public class DruidSegmentReaderTest
+public class DruidSegmentReaderTest extends NullHandlingTest
 {
+  @Rule
+  public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+  private File segmentDirectory;
+
+  private final IndexIO indexIO = TestHelper.getTestIndexIO();
+
+  @Before
+  public void setUp() throws IOException
+  {
+    // Write a segment with two rows in it, with columns: s (string), d (double), cnt (long), met_s (complex).
+    final IncrementalIndex<?> incrementalIndex =
+        IndexBuilder.create()
+                    .schema(
+                        new IncrementalIndexSchema.Builder()
+                            .withDimensionsSpec(
+                                new DimensionsSpec(
+                                    ImmutableList.of(
+                                        StringDimensionSchema.create("s"),
+                                        new DoubleDimensionSchema("d")
+                                    )
+                                )
+                            )
+                            .withMetrics(
+                                new CountAggregatorFactory("cnt"),
+                                new HyperUniquesAggregatorFactory("met_s", "s")
+                            )
+                            .withRollup(false)
+                            .build()
+                    )
+                    .rows(
+                        ImmutableList.of(
+                            new MapBasedInputRow(
+                                DateTimes.of("2000"),
+                                ImmutableList.of("s", "d"),
+                                ImmutableMap.<String, Object>builder()
+                                    .put("s", "foo")
+                                    .put("d", 1.23)
+                                    .build()
+                            ),
+                            new MapBasedInputRow(
+                                DateTimes.of("2000T01"),
+                                ImmutableList.of("s", "d"),
+                                ImmutableMap.<String, Object>builder()
+                                    .put("s", "bar")
+                                    .put("d", 4.56)
+                                    .build()
+                            )
+                        )
+                    )
+                    .buildIncrementalIndex();
+
+    segmentDirectory = temporaryFolder.newFolder();
+
+    try {
+      TestHelper.getTestIndexMergerV9(
+          OnHeapMemorySegmentWriteOutMediumFactory.instance()
+      ).persist(
+          incrementalIndex,
+          segmentDirectory,
+          new IndexSpec(),
+          null
+      );
+    }
+    finally {
+      incrementalIndex.close();
+    }
+  }
+
+  @Test
+  public void testReader() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "millis", DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.all(),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("2000"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("2000T01"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("bar"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderAutoTimestampFormat() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "auto", DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.all(),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("2000"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("2000T01"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("bar"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderWithDimensionExclusions() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "millis", DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(),
+            ImmutableList.of("__time", "s", "cnt", "met_s"),
+            ImmutableList.of()
+        ),
+        ColumnsFilter.all(),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("2000"),
+                ImmutableList.of("d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("2000T01"),
+                ImmutableList.of("d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("bar"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderWithInclusiveColumnsFilter() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "millis", DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.inclusionBased(ImmutableSet.of("__time", "s", "d")),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("2000"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("2000T01"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderWithInclusiveColumnsFilterNoTimestamp() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "millis", DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.inclusionBased(ImmutableSet.of("s", "d")),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("1971"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("1971"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderWithFilter() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "millis", DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.all(),
+        new SelectorDimFilter("d", "1.23", null),
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("2000"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderTimestampFromDouble() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("d", "posix", null),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.all(),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("1970-01-01T00:00:01.000Z"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("1970-01-01T00:00:04.000Z"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("bar"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderTimestampAsPosixIncorrectly() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec("__time", "posix", null),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.all(),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("31969-04-01T00:00:00.000Z"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("31969-05-12T16:00:00.000Z"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("bar"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
+  @Test
+  public void testReaderTimestampSpecDefault() throws IOException
+  {
+    final DruidSegmentReader reader = new DruidSegmentReader(
+        makeInputEntity(Intervals.of("2000/P1D")),
+        indexIO,
+        new TimestampSpec(null, null, DateTimes.of("1971")),
+        new DimensionsSpec(
+            ImmutableList.of(
+                StringDimensionSchema.create("s"),
+                new DoubleDimensionSchema("d")
+            )
+        ),
+        ColumnsFilter.all(),
+        null,
+        temporaryFolder.newFolder()
+    );
+
+    Assert.assertEquals(
+        ImmutableList.of(
+            new MapBasedInputRow(
+                DateTimes.of("1971"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T").getMillis())
+                    .put("s", "foo")
+                    .put("d", 1.23d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("foo"))
+                    .build()
+            ),
+            new MapBasedInputRow(
+                DateTimes.of("1971"),
+                ImmutableList.of("s", "d"),
+                ImmutableMap.<String, Object>builder()
+                    .put("__time", DateTimes.of("2000T01").getMillis())
+                    .put("s", "bar")
+                    .put("d", 4.56d)
+                    .put("cnt", 1L)
+                    .put("met_s", makeHLLC("bar"))
+                    .build()
+            )
+        ),
+        readRows(reader)
+    );
+  }
+
   @Test
   public void testMakeCloseableIteratorFromSequenceAndSegmentFileCloseYielderOnClose() throws IOException
   {
@@ -80,4 +585,65 @@ public void close()
     Assert.assertTrue("File is not closed", isFileClosed.booleanValue());
     Assert.assertTrue("Sequence is not closed", isSequenceClosed.booleanValue());
   }
+
+  private DruidSegmentInputEntity makeInputEntity(final Interval interval)
+  {
+    return new DruidSegmentInputEntity(
+        new SegmentLoader()
+        {
+          @Override
+          public boolean isSegmentLoaded(DataSegment segment)
+          {
+            throw new UnsupportedOperationException("unused");
+          }
+
+          @Override
+          public Segment getSegment(DataSegment segment, boolean lazy, SegmentLazyLoadFailCallback loadFailed)
+          {
+            throw new UnsupportedOperationException("unused");
+          }
+
+          @Override
+          public File getSegmentFiles(DataSegment segment)
+          {
+            return segmentDirectory;
+          }
+
+          @Override
+          public void cleanup(DataSegment segment)
+          {
+            throw new UnsupportedOperationException("unused");
+          }
+        },
+        DataSegment.builder()
+                   .dataSource("ds")
+                   .dimensions(ImmutableList.of("s", "d"))
+                   .metrics(ImmutableList.of("cnt", "met_s"))
+                   .interval(Intervals.of("2000/P1D"))
+                   .version("1")
+                   .size(0)
+                   .build(),
+        interval
+    );
+  }
+
+  private List<InputRow> readRows(final DruidSegmentReader reader) throws IOException
+  {
+    final List<InputRow> rows = new ArrayList<>();
+    try (final CloseableIterator<Map<String, Object>> iterator = reader.intermediateRowIterator()) {
+      while (iterator.hasNext()) {
+        rows.addAll(reader.parseInputRows(iterator.next()));
+      }
+    }
+    return rows;
+  }
+
+  private static HyperLogLogCollector makeHLLC(final String... values)
+  {
+    final HyperLogLogCollector collector = HyperLogLogCollector.makeLatestCollector();
+    for (String value : values) {
+      collector.add(HyperLogLogHash.getDefault().hash(value));
+    }
+    return collector;
+  }
 }
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/input/InputRowSchemasTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/input/InputRowSchemasTest.java
new file mode 100644
index 000000000000..7241a27cc679
--- /dev/null
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/input/InputRowSchemasTest.java
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.input;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import org.apache.druid.common.config.NullHandlingTest;
+import org.apache.druid.data.input.ColumnsFilter;
+import org.apache.druid.data.input.impl.DimensionsSpec;
+import org.apache.druid.data.input.impl.StringDimensionSchema;
+import org.apache.druid.data.input.impl.TimestampSpec;
+import org.apache.druid.math.expr.ExprMacroTable;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.query.aggregation.LongSumAggregatorFactory;
+import org.apache.druid.query.filter.SelectorDimFilter;
+import org.apache.druid.segment.transform.ExpressionTransform;
+import org.apache.druid.segment.transform.TransformSpec;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class InputRowSchemasTest extends NullHandlingTest
+{
+  @Test
+  public void test_createColumnsFilter_normal()
+  {
+    final ColumnsFilter columnsFilter = InputRowSchemas.createColumnsFilter(
+        new TimestampSpec("ts", "auto", null),
+        new DimensionsSpec(
+            ImmutableList.of(StringDimensionSchema.create("foo")),
+            ImmutableList.of(),
+            ImmutableList.of()
+        ),
+        new TransformSpec(
+            new SelectorDimFilter("bar", "x", null),
+            ImmutableList.of(
+                new ExpressionTransform("baz", "qux + 3", ExprMacroTable.nil())
+            )
+        ),
+        new AggregatorFactory[]{
+            new LongSumAggregatorFactory("billy", "bob")
+        }
+    );
+
+    Assert.assertEquals(
+        ColumnsFilter.inclusionBased(
+            ImmutableSet.of(
+                "ts",
+                "foo",
+                "bar",
+                "qux",
+                "bob"
+            )
+        ),
+        columnsFilter
+    );
+  }
+
+  @Test
+  public void test_createColumnsFilter_schemaless()
+  {
+    final ColumnsFilter columnsFilter = InputRowSchemas.createColumnsFilter(
+        new TimestampSpec("ts", "auto", null),
+        new DimensionsSpec(
+            ImmutableList.of(),
+            ImmutableList.of("ts", "foo", "bar", "qux", "bob"),
+            ImmutableList.of()
+        ),
+        new TransformSpec(
+            new SelectorDimFilter("bar", "x", null),
+            ImmutableList.of(
+                new ExpressionTransform("baz", "qux + 3", ExprMacroTable.nil())
+            )
+        ),
+        new AggregatorFactory[]{
+            new LongSumAggregatorFactory("billy", "bob")
+        }
+    );
+
+    Assert.assertEquals(
+        ColumnsFilter.exclusionBased(
+            ImmutableSet.of(
+                "foo"
+            )
+        ),
+        columnsFilter
+    );
+  }
+}
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/overlord/SingleTaskBackgroundRunnerTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/overlord/SingleTaskBackgroundRunnerTest.java
index 49b2ce7ae371..120c7090d93d 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/overlord/SingleTaskBackgroundRunnerTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/overlord/SingleTaskBackgroundRunnerTest.java
@@ -89,7 +89,8 @@ public void setup() throws IOException
         true,
         null,
         null,
-        null
+        null,
+        false
     );
     final ServiceEmitter emitter = new NoopServiceEmitter();
     final TaskToolboxFactory toolboxFactory = new TaskToolboxFactory(
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/overlord/TaskLifecycleTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/overlord/TaskLifecycleTest.java
index 8bb8e3ef6274..d39905e91814 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/overlord/TaskLifecycleTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/overlord/TaskLifecycleTest.java
@@ -599,7 +599,7 @@ private TaskToolboxFactory setUpTaskToolboxFactory(
         new TaskAuditLogConfig(true)
     );
     File tmpDir = temporaryFolder.newFolder();
-    taskConfig = new TaskConfig(tmpDir.toString(), null, null, 50000, null, false, null, null, null);
+    taskConfig = new TaskConfig(tmpDir.toString(), null, null, 50000, null, false, null, null, null, false);
 
     return new TaskToolboxFactory(
         taskConfig,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/RecordSupplierInputSourceTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/RecordSupplierInputSourceTest.java
index fba76878d7ea..036f230532cc 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/RecordSupplierInputSourceTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/RecordSupplierInputSourceTest.java
@@ -21,6 +21,7 @@
 
 import com.google.common.collect.Maps;
 import org.apache.commons.lang3.RandomStringUtils;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputFormat;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowSchema;
@@ -79,7 +80,7 @@ public void testRead() throws IOException
         new InputRowSchema(
             new TimestampSpec("col_0", "auto", null),
             new DimensionsSpec(DimensionsSpec.getDefaultSchemas(colNames.subList(1, colNames.size()))),
-            Collections.emptyList()
+            ColumnsFilter.all()
         ),
         inputFormat,
         temporaryFolder.newFolder()
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/StreamChunkParserTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/StreamChunkParserTest.java
index 97dc28050359..1cab704a2eff 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/StreamChunkParserTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/seekablestream/StreamChunkParserTest.java
@@ -21,6 +21,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputEntity;
 import org.apache.druid.data.input.InputEntityReader;
 import org.apache.druid.data.input.InputRow;
@@ -109,7 +110,7 @@ public void testWithNullParserAndInputformatParseProperly() throws IOException
     final StreamChunkParser<ByteEntity> chunkParser = new StreamChunkParser<>(
         null,
         inputFormat,
-        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, Collections.emptyList()),
+        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, ColumnsFilter.all()),
         TransformSpec.NONE,
         temporaryFolder.newFolder(),
         row -> true,
@@ -157,7 +158,7 @@ public void testBothParserAndInputFormatParseProperlyUsingInputFormat() throws I
     final StreamChunkParser<ByteEntity> chunkParser = new StreamChunkParser<>(
         parser,
         inputFormat,
-        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, Collections.emptyList()),
+        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, ColumnsFilter.all()),
         TransformSpec.NONE,
         temporaryFolder.newFolder(),
         row -> true,
@@ -179,7 +180,7 @@ public void parseEmptyNotEndOfShard() throws IOException
     final StreamChunkParser<ByteEntity> chunkParser = new StreamChunkParser<>(
         null,
         inputFormat,
-        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, Collections.emptyList()),
+        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, ColumnsFilter.all()),
         TransformSpec.NONE,
         temporaryFolder.newFolder(),
         row -> true,
@@ -202,7 +203,7 @@ public void parseEmptyEndOfShard() throws IOException
     final StreamChunkParser<ByteEntity> chunkParser = new StreamChunkParser<>(
         null,
         inputFormat,
-        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, Collections.emptyList()),
+        new InputRowSchema(TIMESTAMP_SPEC, DimensionsSpec.EMPTY, ColumnsFilter.all()),
         TransformSpec.NONE,
         temporaryFolder.newFolder(),
         row -> true,
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskManagerTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskManagerTest.java
index 8e5984c37183..dbc223394c56 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskManagerTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskManagerTest.java
@@ -88,7 +88,8 @@ private WorkerTaskManager createWorkerTaskManager()
         false,
         null,
         null,
-        null
+        null,
+        false
     );
     TaskActionClientFactory taskActionClientFactory = EasyMock.createNiceMock(TaskActionClientFactory.class);
     TaskActionClient taskActionClient = EasyMock.createNiceMock(TaskActionClient.class);
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskMonitorTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskMonitorTest.java
index b0bdbc89cc07..fdf7aa44c2f2 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskMonitorTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/worker/WorkerTaskMonitorTest.java
@@ -162,7 +162,8 @@ private WorkerTaskMonitor createTaskMonitor()
         false,
         null,
         null,
-        null
+        null,
+        false
     );
     TaskActionClientFactory taskActionClientFactory = EasyMock.createNiceMock(TaskActionClientFactory.class);
     TaskActionClient taskActionClient = EasyMock.createNiceMock(TaskActionClient.class);
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerAutoCleanupTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerAutoCleanupTest.java
index dcce4809c4aa..76f26fe92da6 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerAutoCleanupTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerAutoCleanupTest.java
@@ -87,7 +87,8 @@ public Period getIntermediaryPartitionTimeout()
         false,
         null,
         null,
-        ImmutableList.of(new StorageLocationConfig(tempDir.newFolder(), null, null))
+        ImmutableList.of(new StorageLocationConfig(tempDir.newFolder(), null, null)),
+        false
     );
     final IndexingServiceClient indexingServiceClient = new NoopIndexingServiceClient()
     {
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerManualAddAndDeleteTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerManualAddAndDeleteTest.java
index 4db1b39b809e..3c87bf4074d0 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerManualAddAndDeleteTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/IntermediaryDataManagerManualAddAndDeleteTest.java
@@ -70,7 +70,8 @@ public void setup() throws IOException
         false,
         null,
         null,
-        ImmutableList.of(new StorageLocationConfig(intermediarySegmentsLocation, 600L, null))
+        ImmutableList.of(new StorageLocationConfig(intermediarySegmentsLocation, 600L, null)),
+        false
     );
     final IndexingServiceClient indexingServiceClient = new NoopIndexingServiceClient();
     intermediaryDataManager = new IntermediaryDataManager(workerConfig, taskConfig, indexingServiceClient);
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleDataSegmentPusherTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleDataSegmentPusherTest.java
index 0604742f100c..54f6c0eef724 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleDataSegmentPusherTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleDataSegmentPusherTest.java
@@ -69,7 +69,8 @@ public void setup() throws IOException
         false,
         null,
         null,
-        ImmutableList.of(new StorageLocationConfig(temporaryFolder.newFolder(), null, null))
+        ImmutableList.of(new StorageLocationConfig(temporaryFolder.newFolder(), null, null)),
+        false
     );
     final IndexingServiceClient indexingServiceClient = new NoopIndexingServiceClient();
     intermediaryDataManager = new IntermediaryDataManager(workerConfig, taskConfig, indexingServiceClient);
diff --git a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleResourceTest.java b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleResourceTest.java
index bd1b2117042f..741956a53f7b 100644
--- a/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleResourceTest.java
+++ b/indexing-service/src/test/java/org/apache/druid/indexing/worker/shuffle/ShuffleResourceTest.java
@@ -95,7 +95,8 @@ public Period getIntermediaryPartitionTimeout()
         false,
         null,
         null,
-        ImmutableList.of(new StorageLocationConfig(tempDir.newFolder(), null, null))
+        ImmutableList.of(new StorageLocationConfig(tempDir.newFolder(), null, null)),
+        false
     );
     final IndexingServiceClient indexingServiceClient = new NoopIndexingServiceClient()
     {
diff --git a/integration-tests/docker/environment-configs/common b/integration-tests/docker/environment-configs/common
index 72c797b61b75..815596f7836e 100644
--- a/integration-tests/docker/environment-configs/common
+++ b/integration-tests/docker/environment-configs/common
@@ -68,3 +68,7 @@ druid_indexer_logs_directory=/shared/tasklogs
 druid_sql_enable=true
 druid_extensions_hadoopDependenciesDir=/shared/hadoop-dependencies
 druid_request_logging_type=slf4j
+
+# Testing the legacy config from https://github.com/apache/druid/pull/10267
+# Can remove this when the flag is no longer needed
+druid_indexer_task_ignoreTimestampSpecForDruidInputSource=true
diff --git a/integration-tests/src/test/java/org/apache/druid/tests/coordinator/duty/ITAutoCompactionTest.java b/integration-tests/src/test/java/org/apache/druid/tests/coordinator/duty/ITAutoCompactionTest.java
index 833e5ebde80c..e2b141f0f395 100644
--- a/integration-tests/src/test/java/org/apache/druid/tests/coordinator/duty/ITAutoCompactionTest.java
+++ b/integration-tests/src/test/java/org/apache/druid/tests/coordinator/duty/ITAutoCompactionTest.java
@@ -129,7 +129,7 @@ public void testAutoCompactionDutySubmitAndVerifyCompaction() throws Exception
           fullDatasourceName,
           AutoCompactionSnapshot.AutoCompactionScheduleStatus.RUNNING,
           0,
-          22482,
+          22481,
           0,
           0,
           3,
@@ -275,7 +275,7 @@ public void testAutoCompactionDutyCanUpdateTaskSlots() throws Exception
           fullDatasourceName,
           AutoCompactionSnapshot.AutoCompactionScheduleStatus.RUNNING,
           0,
-          22482,
+          22481,
           0,
           0,
           3,
diff --git a/integration-tests/src/test/resources/indexer/wikipedia_parallel_druid_input_source_index_task.json b/integration-tests/src/test/resources/indexer/wikipedia_parallel_druid_input_source_index_task.json
index 91702a413574..46af17af5984 100644
--- a/integration-tests/src/test/resources/indexer/wikipedia_parallel_druid_input_source_index_task.json
+++ b/integration-tests/src/test/resources/indexer/wikipedia_parallel_druid_input_source_index_task.json
@@ -10,7 +10,8 @@
         ]
       },
       "timestampSpec": {
-        "column": "timestamp"
+        "column": "ignored-see-ignoreTimestampSpecForDruidInputSource",
+        "format": "iso"
       },
       "metricsSpec": [
         {
diff --git a/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task.json b/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task.json
index 3a5934cf4d37..cf2415c2b45c 100644
--- a/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task.json
+++ b/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task.json
@@ -24,7 +24,7 @@
             },
             "timestampSpec": {
                 "column": "__time",
-                "format": "iso"
+                "format": "millis"
             },
             "dimensionsSpec": {
                 "dimensionExclusions" : ["robot", "continent"]
diff --git a/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task_with_transforms.json b/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task_with_transforms.json
index 3e8a44c5c592..2c2b0372a56c 100644
--- a/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task_with_transforms.json
+++ b/integration-tests/src/test/resources/indexer/wikipedia_reindex_druid_input_source_task_with_transforms.json
@@ -24,7 +24,7 @@
             },
             "timestampSpec": {
                 "column": "__time",
-                "format": "iso"
+                "format": "millis"
             },
             "dimensionsSpec": {
                 "dimensions": [
diff --git a/processing/src/main/java/org/apache/druid/segment/transform/ExpressionTransform.java b/processing/src/main/java/org/apache/druid/segment/transform/ExpressionTransform.java
index 16bad318a7fc..2ace9b06bf14 100644
--- a/processing/src/main/java/org/apache/druid/segment/transform/ExpressionTransform.java
+++ b/processing/src/main/java/org/apache/druid/segment/transform/ExpressionTransform.java
@@ -23,6 +23,7 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
+import com.google.common.base.Suppliers;
 import org.apache.druid.data.input.Row;
 import org.apache.druid.math.expr.Expr;
 import org.apache.druid.math.expr.ExprMacroTable;
@@ -32,12 +33,15 @@
 
 import java.util.List;
 import java.util.Objects;
+import java.util.Set;
+import java.util.function.Supplier;
 
 public class ExpressionTransform implements Transform
 {
   private final String name;
   private final String expression;
   private final ExprMacroTable macroTable;
+  private final Supplier<Expr> parsedExpression;
 
   @JsonCreator
   public ExpressionTransform(
@@ -49,6 +53,9 @@ public ExpressionTransform(
     this.name = Preconditions.checkNotNull(name, "name");
     this.expression = Preconditions.checkNotNull(expression, "expression");
     this.macroTable = macroTable;
+    this.parsedExpression = Suppliers.memoize(
+        () -> Parser.parse(expression, Preconditions.checkNotNull(this.macroTable, "macroTable"))
+    )::get;
   }
 
   @JsonProperty
@@ -67,8 +74,13 @@ public String getExpression()
   @Override
   public RowFunction getRowFunction()
   {
-    final Expr expr = Parser.parse(expression, Preconditions.checkNotNull(this.macroTable, "macroTable"));
-    return new ExpressionRowFunction(expr);
+    return new ExpressionRowFunction(parsedExpression.get());
+  }
+
+  @Override
+  public Set<String> getRequiredColumns()
+  {
+    return parsedExpression.get().analyzeInputs().getRequiredBindings();
   }
 
   static class ExpressionRowFunction implements RowFunction
diff --git a/processing/src/main/java/org/apache/druid/segment/transform/Transform.java b/processing/src/main/java/org/apache/druid/segment/transform/Transform.java
index a481a4c08a11..8b6f75fa2d81 100644
--- a/processing/src/main/java/org/apache/druid/segment/transform/Transform.java
+++ b/processing/src/main/java/org/apache/druid/segment/transform/Transform.java
@@ -23,6 +23,8 @@
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
 import org.apache.druid.guice.annotations.ExtensionPoint;
 
+import java.util.Set;
+
 /**
  * A row transform that is part of a {@link TransformSpec}. Transforms allow adding new fields to input rows. Each
  * one has a "name" (the name of the new field) which can be referred to by DimensionSpecs, AggregatorFactories, etc.
@@ -52,4 +54,9 @@ public interface Transform
    * as output.
    */
   RowFunction getRowFunction();
+
+  /**
+   * Returns the names of all columns that this transform is going to read.
+   */
+  Set<String> getRequiredColumns();
 }
diff --git a/processing/src/main/java/org/apache/druid/segment/transform/TransformSpec.java b/processing/src/main/java/org/apache/druid/segment/transform/TransformSpec.java
index 6de7ac9363c8..1391da394b01 100644
--- a/processing/src/main/java/org/apache/druid/segment/transform/TransformSpec.java
+++ b/processing/src/main/java/org/apache/druid/segment/transform/TransformSpec.java
@@ -126,6 +126,21 @@ public Transformer toTransformer()
     return new Transformer(this);
   }
 
+  public Set<String> getRequiredColumns()
+  {
+    final Set<String> requiredColumns = new HashSet<>();
+
+    if (filter != null) {
+      requiredColumns.addAll(filter.getRequiredColumns());
+    }
+
+    for (Transform transform : transforms) {
+      requiredColumns.addAll(transform.getRequiredColumns());
+    }
+
+    return requiredColumns;
+  }
+
   @Override
   public boolean equals(final Object o)
   {
diff --git a/server/src/test/java/org/apache/druid/segment/indexing/TransformSpecTest.java b/processing/src/test/java/org/apache/druid/segment/transform/TransformSpecTest.java
similarity index 91%
rename from server/src/test/java/org/apache/druid/segment/indexing/TransformSpecTest.java
rename to processing/src/test/java/org/apache/druid/segment/transform/TransformSpecTest.java
index 763a924f8c20..00d491e10973 100644
--- a/server/src/test/java/org/apache/druid/segment/indexing/TransformSpecTest.java
+++ b/processing/src/test/java/org/apache/druid/segment/transform/TransformSpecTest.java
@@ -17,11 +17,12 @@
  * under the License.
  */
 
-package org.apache.druid.segment.indexing;
+package org.apache.druid.segment.transform;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.impl.DimensionsSpec;
 import org.apache.druid.data.input.impl.InputRowParser;
@@ -33,8 +34,6 @@
 import org.apache.druid.query.filter.AndDimFilter;
 import org.apache.druid.query.filter.SelectorDimFilter;
 import org.apache.druid.segment.TestHelper;
-import org.apache.druid.segment.transform.ExpressionTransform;
-import org.apache.druid.segment.transform.TransformSpec;
 import org.apache.druid.testing.InitializedNullHandlingTest;
 import org.junit.Assert;
 import org.junit.Test;
@@ -80,6 +79,11 @@ public void testTransforms()
         )
     );
 
+    Assert.assertEquals(
+        ImmutableSet.of("x", "y", "a", "b", "f", "g"),
+        transformSpec.getRequiredColumns()
+    );
+
     final InputRowParser<Map<String, Object>> parser = transformSpec.decorate(PARSER);
     final InputRow row = parser.parseBatch(ROW1).get(0);
 
@@ -108,6 +112,11 @@ public void testTransformOverwriteField()
         )
     );
 
+    Assert.assertEquals(
+        ImmutableSet.of("x", "y"),
+        transformSpec.getRequiredColumns()
+    );
+
     final InputRowParser<Map<String, Object>> parser = transformSpec.decorate(PARSER);
     final InputRow row = parser.parseBatch(ROW1).get(0);
 
@@ -139,6 +148,12 @@ public void testFilterOnTransforms()
         )
     );
 
+    Assert.assertEquals(
+        ImmutableSet.of("x", "f", "g", "y", "a", "b"),
+        transformSpec.getRequiredColumns()
+    );
+
+
     final InputRowParser<Map<String, Object>> parser = transformSpec.decorate(PARSER);
     Assert.assertNotNull(parser.parseBatch(ROW1).get(0));
     Assert.assertNull(parser.parseBatch(ROW2).get(0));
@@ -154,6 +169,12 @@ public void testTransformTimeFromOtherFields()
         )
     );
 
+    Assert.assertEquals(
+        ImmutableSet.of("a", "b"),
+        transformSpec.getRequiredColumns()
+    );
+
+
     final InputRowParser<Map<String, Object>> parser = transformSpec.decorate(PARSER);
     final InputRow row = parser.parseBatch(ROW1).get(0);
 
@@ -172,6 +193,11 @@ public void testTransformTimeFromTime()
         )
     );
 
+    Assert.assertEquals(
+        ImmutableSet.of("__time"),
+        transformSpec.getRequiredColumns()
+    );
+
     final InputRowParser<Map<String, Object>> parser = transformSpec.decorate(PARSER);
     final InputRow row = parser.parseBatch(ROW1).get(0);
 
diff --git a/server/src/main/java/org/apache/druid/segment/indexing/DataSchema.java b/server/src/main/java/org/apache/druid/segment/indexing/DataSchema.java
index f36f754b50e8..04be8c49bfb3 100644
--- a/server/src/main/java/org/apache/druid/segment/indexing/DataSchema.java
+++ b/server/src/main/java/org/apache/druid/segment/indexing/DataSchema.java
@@ -27,8 +27,8 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
-import com.google.common.collect.Sets;
 import org.apache.druid.common.utils.IdUtils;
+import org.apache.druid.data.input.impl.DimensionSchema;
 import org.apache.druid.data.input.impl.DimensionsSpec;
 import org.apache.druid.data.input.impl.InputRowParser;
 import org.apache.druid.data.input.impl.ParseSpec;
@@ -36,6 +36,7 @@
 import org.apache.druid.java.util.common.IAE;
 import org.apache.druid.java.util.common.logger.Logger;
 import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.segment.column.ColumnHolder;
 import org.apache.druid.segment.indexing.granularity.GranularitySpec;
 import org.apache.druid.segment.indexing.granularity.UniformGranularitySpec;
 import org.apache.druid.segment.transform.TransformSpec;
@@ -45,8 +46,7 @@
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
-import java.util.regex.Pattern;
-import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 
 /**
@@ -55,7 +55,6 @@
 public class DataSchema
 {
   private static final Logger log = new Logger(DataSchema.class);
-  private static final Pattern INVALIDCHARS = Pattern.compile("(?s).*[^\\S ].*");
   private final String dataSource;
   private final AggregatorFactory[] aggregators;
   private final GranularitySpec granularitySpec;
@@ -150,35 +149,47 @@ private static void validateDatasourceName(String dataSource)
     IdUtils.validateId("dataSource", dataSource);
   }
 
+  /**
+   * Computes the {@link DimensionsSpec} that we will actually use. It is derived from, but not necessarily identical
+   * to, the one that we were given.
+   */
   private static DimensionsSpec computeDimensionsSpec(
-      TimestampSpec timestampSpec,
-      DimensionsSpec dimensionsSpec,
-      AggregatorFactory[] aggregators
+      final TimestampSpec timestampSpec,
+      final DimensionsSpec dimensionsSpec,
+      final AggregatorFactory[] aggregators
   )
   {
-    final Set<String> dimensionExclusions = new HashSet<>();
-
-    final String timestampColumn = timestampSpec.getTimestampColumn();
-    if (!(dimensionsSpec.hasCustomDimensions() && dimensionsSpec.getDimensionNames().contains(timestampColumn))) {
-      dimensionExclusions.add(timestampColumn);
-    }
-
-    for (AggregatorFactory aggregator : aggregators) {
-      dimensionExclusions.addAll(aggregator.requiredFields());
-      dimensionExclusions.add(aggregator.getName());
-    }
+    final Set<String> inputFieldNames = new HashSet<>();
+    final Set<String> outputFieldNames = new HashSet<>();
+
+    // Populate inputFieldNames.
+    inputFieldNames.add(timestampSpec.getTimestampColumn());
+    inputFieldNames.addAll(dimensionsSpec.getDimensionNames());
+    Arrays.stream(aggregators)
+          .flatMap(aggregator -> aggregator.requiredFields().stream())
+          .forEach(inputFieldNames::add);
+
+    // Populate outputFieldNames, validating along the way for lack of duplicates.
+    outputFieldNames.add(ColumnHolder.TIME_COLUMN_NAME);
+
+    Stream.concat(
+        dimensionsSpec.getDimensions().stream().map(DimensionSchema::getName),
+        Arrays.stream(aggregators).map(AggregatorFactory::getName)
+    ).forEach(
+        field -> {
+          if (!outputFieldNames.add(field)) {
+            throw new IAE("Cannot specify field [%s] more than once", field);
+          }
+        }
+    );
 
-    final Set<String> metSet = Arrays.stream(aggregators).map(AggregatorFactory::getName).collect(Collectors.toSet());
-    final Set<String> dimSet = new HashSet<>(dimensionsSpec.getDimensionNames());
-    final Set<String> overlap = Sets.intersection(metSet, dimSet);
-    if (!overlap.isEmpty()) {
-      throw new IAE(
-          "Cannot have overlapping dimensions and metrics of the same name. Please change the name of the metric. Overlap: %s",
-          overlap
-      );
-    }
+    // Set up additional exclusions: all inputs and outputs, minus defined dimensions.
+    final Set<String> additionalDimensionExclusions = new HashSet<>();
+    additionalDimensionExclusions.addAll(inputFieldNames);
+    additionalDimensionExclusions.addAll(outputFieldNames);
+    additionalDimensionExclusions.removeAll(dimensionsSpec.getDimensionNames());
 
-    return dimensionsSpec.withDimensionExclusions(Sets.difference(dimensionExclusions, dimSet));
+    return dimensionsSpec.withDimensionExclusions(additionalDimensionExclusions);
   }
 
   @JsonProperty
diff --git a/server/src/test/java/org/apache/druid/metadata/input/SqlInputSourceTest.java b/server/src/test/java/org/apache/druid/metadata/input/SqlInputSourceTest.java
index caeb39e397c3..1e65c7b486c6 100644
--- a/server/src/test/java/org/apache/druid/metadata/input/SqlInputSourceTest.java
+++ b/server/src/test/java/org/apache/druid/metadata/input/SqlInputSourceTest.java
@@ -27,6 +27,7 @@
 import nl.jqno.equalsverifier.EqualsVerifier;
 import org.apache.commons.dbcp2.BasicDataSource;
 import org.apache.commons.io.FileUtils;
+import org.apache.druid.data.input.ColumnsFilter;
 import org.apache.druid.data.input.InputFormat;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.data.input.InputRowListPlusRawValues;
@@ -54,7 +55,6 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
@@ -80,7 +80,7 @@ public class SqlInputSourceTest
           new ArrayList<>(),
           new ArrayList<>()
       ),
-      Collections.emptyList()
+      ColumnsFilter.all()
   );
   @Rule
   public final TestDerbyConnector.DerbyConnectorRule derbyConnectorRule = new TestDerbyConnector.DerbyConnectorRule();
diff --git a/server/src/test/java/org/apache/druid/segment/indexing/DataSchemaTest.java b/server/src/test/java/org/apache/druid/segment/indexing/DataSchemaTest.java
index 83fc9c66e36d..0b9eb398e2ad 100644
--- a/server/src/test/java/org/apache/druid/segment/indexing/DataSchemaTest.java
+++ b/server/src/test/java/org/apache/druid/segment/indexing/DataSchemaTest.java
@@ -101,7 +101,7 @@ public void testDefaultExclusions()
     );
 
     Assert.assertEquals(
-        ImmutableSet.of("time", "col1", "col2", "metric1", "metric2"),
+        ImmutableSet.of("__time", "time", "col1", "col2", "metric1", "metric2"),
         schema.getDimensionsSpec().getDimensionExclusions()
     );
   }
@@ -139,7 +139,7 @@ public void testExplicitInclude()
     );
 
     Assert.assertEquals(
-        ImmutableSet.of("dimC", "col1", "metric1", "metric2"),
+        ImmutableSet.of("__time", "dimC", "col1", "metric1", "metric2"),
         schema.getParser().getParseSpec().getDimensionsSpec().getDimensionExclusions()
     );
   }
@@ -409,7 +409,7 @@ public void testSerde() throws Exception
         actual.getParser().getParseSpec(),
         new JSONParseSpec(
             new TimestampSpec("xXx", null, null),
-            new DimensionsSpec(null, Arrays.asList("metric1", "xXx", "col1"), null),
+            new DimensionsSpec(null, Arrays.asList("__time", "metric1", "xXx", "col1"), null),
             null,
             null,
             null
diff --git a/web-console/e2e-tests/reindexing.spec.ts b/web-console/e2e-tests/reindexing.spec.ts
index a14262a8ab28..d32a6d91160e 100644
--- a/web-console/e2e-tests/reindexing.spec.ts
+++ b/web-console/e2e-tests/reindexing.spec.ts
@@ -115,50 +115,50 @@ function validateConnectLocalData(preview: string) {
   expect(firstLine).toBe(
     'Druid row: {' +
       '"__time":1442018818771' +
-      ',"isRobot":"false"' +
-      ',"countryIsoCode":null' +
-      ',"added":"36"' +
-      ',"regionName":null' +
       ',"channel":"#en.wikipedia"' +
-      ',"delta":"36"' +
-      ',"isUnpatrolled":"false"' +
-      ',"isNew":"false"' +
-      ',"isMinor":"false"' +
+      ',"comment":"added project"' +
       ',"isAnonymous":"false"' +
-      ',"deleted":"0"' +
-      ',"cityName":null' +
-      ',"metroCode":null' +
+      ',"isMinor":"false"' +
+      ',"isNew":"false"' +
+      ',"isRobot":"false"' +
+      ',"isUnpatrolled":"false"' +
       ',"namespace":"Talk"' +
-      ',"comment":"added project"' +
-      ',"countryName":null' +
       ',"page":"Talk:Oswald Tilghman"' +
       ',"user":"GELongstreet"' +
+      ',"added":"36"' +
+      ',"deleted":"0"' +
+      ',"delta":"36"' +
+      ',"cityName":null' +
+      ',"countryIsoCode":null' +
+      ',"countryName":null' +
       ',"regionIsoCode":null' +
+      ',"regionName":null' +
+      ',"metroCode":null' +
       '}',
   );
   const lastLine = lines[lines.length - 1];
   expect(lastLine).toBe(
     'Druid row: {' +
       '"__time":1442020314823' +
-      ',"isRobot":"false"' +
-      ',"countryIsoCode":null' +
-      ',"added":"1"' +
-      ',"regionName":null' +
       ',"channel":"#en.wikipedia"' +
-      ',"delta":"1"' +
-      ',"isUnpatrolled":"false"' +
-      ',"isNew":"false"' +
-      ',"isMinor":"true"' +
+      ',"comment":"/* History */[[WP:AWB/T|Typo fixing]], [[WP:AWB/T|typo(s) fixed]]: nothern → northern using [[Project:AWB|AWB]]"' +
       ',"isAnonymous":"false"' +
-      ',"deleted":"0"' +
-      ',"cityName":null' +
-      ',"metroCode":null' +
+      ',"isMinor":"true"' +
+      ',"isNew":"false"' +
+      ',"isRobot":"false"' +
+      ',"isUnpatrolled":"false"' +
       ',"namespace":"Main"' +
-      ',"comment":"/* History */[[WP:AWB/T|Typo fixing]], [[WP:AWB/T|typo(s) fixed]]: nothern → northern using [[Project:AWB|AWB]]"' +
-      ',"countryName":null' +
       ',"page":"Hapoel Katamon Jerusalem F.C."' +
       ',"user":"The Quixotic Potato"' +
+      ',"added":"1"' +
+      ',"deleted":"0"' +
+      ',"delta":"1"' +
+      ',"cityName":null' +
+      ',"countryIsoCode":null' +
+      ',"countryName":null' +
       ',"regionIsoCode":null' +
+      ',"regionName":null' +
+      ',"metroCode":null' +
       '}',
   );
 }
diff --git a/web-console/src/druid-models/ingestion-spec.tsx b/web-console/src/druid-models/ingestion-spec.tsx
index d4c9bdca89fe..53146f55fb10 100644
--- a/web-console/src/druid-models/ingestion-spec.tsx
+++ b/web-console/src/druid-models/ingestion-spec.tsx
@@ -485,32 +485,6 @@ export function getIoConfigFormFields(ingestionComboType: IngestionComboType): F
             </p>
           ),
         },
-        {
-          name: 'inputSource.dimensions',
-          label: 'Dimensions',
-          type: 'string-array',
-          placeholder: '(optional)',
-          hideInMore: true,
-          info: (
-            <p>
-              The list of dimensions to select. If left empty, no dimensions are returned. If left
-              null or not defined, all dimensions are returned.
-            </p>
-          ),
-        },
-        {
-          name: 'inputSource.metrics',
-          label: 'Metrics',
-          type: 'string-array',
-          placeholder: '(optional)',
-          hideInMore: true,
-          info: (
-            <p>
-              The list of metrics to select. If left empty, no metrics are returned. If left null or
-              not defined, all metrics are selected.
-            </p>
-          ),
-        },
         {
           name: 'inputSource.filter',
           label: 'Filter',
diff --git a/web-console/src/druid-models/timestamp-spec.tsx b/web-console/src/druid-models/timestamp-spec.tsx
index b6c595b17dab..f6a8263998fa 100644
--- a/web-console/src/druid-models/timestamp-spec.tsx
+++ b/web-console/src/druid-models/timestamp-spec.tsx
@@ -32,11 +32,18 @@ import { Transform } from './transform-spec';
 
 const NO_SUCH_COLUMN = '!!!_no_such_column_!!!';
 
+export const TIME_COLUMN = '__time';
+
 export const PLACEHOLDER_TIMESTAMP_SPEC: TimestampSpec = {
   column: NO_SUCH_COLUMN,
   missingValue: '1970-01-01T00:00:00Z',
 };
 
+export const REINDEX_TIMESTAMP_SPEC: TimestampSpec = {
+  column: TIME_COLUMN,
+  format: 'millis',
+};
+
 export const CONSTANT_TIMESTAMP_SPEC: TimestampSpec = {
   column: NO_SUCH_COLUMN,
   missingValue: '2010-01-01T00:00:00Z',
@@ -48,7 +55,7 @@ export function getTimestampSchema(spec: IngestionSpec): TimestampSchema {
   const transforms: Transform[] =
     deepGet(spec, 'spec.dataSchema.transformSpec.transforms') || EMPTY_ARRAY;
 
-  const timeTransform = transforms.find(transform => transform.name === '__time');
+  const timeTransform = transforms.find(transform => transform.name === TIME_COLUMN);
   if (timeTransform) return 'expression';
 
   const timestampSpec = deepGet(spec, 'spec.dataSchema.timestampSpec') || EMPTY_OBJECT;
@@ -74,7 +81,7 @@ export function getTimestampSpecExpressionFromSpec(spec: IngestionSpec): string
   const transforms: Transform[] =
     deepGet(spec, 'spec.dataSchema.transformSpec.transforms') || EMPTY_ARRAY;
 
-  const timeTransform = transforms.find(transform => transform.name === '__time');
+  const timeTransform = transforms.find(transform => transform.name === TIME_COLUMN);
   if (!timeTransform) return;
   return timeTransform.expression;
 }
diff --git a/web-console/src/utils/sampler.ts b/web-console/src/utils/sampler.ts
index 3f37c9edc951..0bd9ae8e36c9 100644
--- a/web-console/src/utils/sampler.ts
+++ b/web-console/src/utils/sampler.ts
@@ -29,6 +29,8 @@ import {
   isDruidSource,
   MetricSpec,
   PLACEHOLDER_TIMESTAMP_SPEC,
+  REINDEX_TIMESTAMP_SPEC,
+  TIME_COLUMN,
   TimestampSpec,
   Transform,
   TransformSpec,
@@ -152,13 +154,13 @@ export function headerFromSampleResponse(options: HeaderFromSampleResponseOption
 
   let columns = sortWithPrefixSuffix(
     dedupe(sampleResponse.data.flatMap(s => (s.parsed ? Object.keys(s.parsed) : []))).sort(),
-    columnOrder || ['__time'],
+    columnOrder || [TIME_COLUMN],
     suffixColumnOrder || [],
     alphanumericCompare,
   );
 
   if (ignoreTimeColumn) {
-    columns = columns.filter(c => c !== '__time');
+    columns = columns.filter(c => c !== TIME_COLUMN);
   }
 
   return columns;
@@ -290,7 +292,7 @@ export async function sampleForConnect(
       ioConfig,
       dataSchema: {
         dataSource: 'sample',
-        timestampSpec: PLACEHOLDER_TIMESTAMP_SPEC,
+        timestampSpec: reingestMode ? REINDEX_TIMESTAMP_SPEC : PLACEHOLDER_TIMESTAMP_SPEC,
         dimensionsSpec: {},
       },
     } as any,
@@ -338,13 +340,15 @@ export async function sampleForParser(
     sampleStrategy,
   );
 
+  const reingestMode = isDruidSource(spec);
+
   const sampleSpec: SampleSpec = {
     type: samplerType,
     spec: {
       ioConfig,
       dataSchema: {
         dataSource: 'sample',
-        timestampSpec: PLACEHOLDER_TIMESTAMP_SPEC,
+        timestampSpec: reingestMode ? REINDEX_TIMESTAMP_SPEC : PLACEHOLDER_TIMESTAMP_SPEC,
         dimensionsSpec: {},
       },
     },
@@ -398,7 +402,7 @@ export async function sampleForTimestamp(
         dimensionsSpec: {},
         timestampSpec,
         transformSpec: {
-          transforms: transforms.filter(transform => transform.name === '__time'),
+          transforms: transforms.filter(transform => transform.name === TIME_COLUMN),
         },
       },
     },
@@ -459,7 +463,7 @@ export async function sampleForTransform(
       headerFromSampleResponse({
         sampleResponse: sampleResponseHack,
         ignoreTimeColumn: true,
-        columnOrder: ['__time'].concat(inputFormatColumns),
+        columnOrder: [TIME_COLUMN].concat(inputFormatColumns),
       }).concat(transforms.map(t => t.name)),
     );
   }
@@ -518,7 +522,7 @@ export async function sampleForFilter(
       headerFromSampleResponse({
         sampleResponse: sampleResponseHack,
         ignoreTimeColumn: true,
-        columnOrder: ['__time'].concat(inputFormatColumns),
+        columnOrder: [TIME_COLUMN].concat(inputFormatColumns),
       }).concat(transforms.map(t => t.name)),
     );
   }
diff --git a/web-console/src/views/load-data-view/load-data-view.tsx b/web-console/src/views/load-data-view/load-data-view.tsx
index 783b44883df3..447c9f64c2ad 100644
--- a/web-console/src/views/load-data-view/load-data-view.tsx
+++ b/web-console/src/views/load-data-view/load-data-view.tsx
@@ -55,6 +55,7 @@ import {
 } from '../../components';
 import { FormGroupWithInfo } from '../../components/form-group-with-info/form-group-with-info';
 import { AsyncActionDialog } from '../../dialogs';
+import { TIME_COLUMN } from '../../druid-models';
 import {
   addTimestampTransform,
   adjustId,
@@ -1221,8 +1222,8 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
 
             if (druidSource) {
               let newSpec = deepSet(spec, 'spec.dataSchema.timestampSpec', {
-                column: '__time',
-                format: 'iso',
+                column: TIME_COLUMN,
+                format: 'millis',
               });
 
               if (typeof inputData.rollup === 'boolean') {
@@ -1247,7 +1248,7 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
                   newSpec,
                   'spec.dataSchema.dimensionsSpec.dimensions',
                   Object.keys(inputData.columns)
-                    .filter(k => k !== '__time' && !aggregators[k])
+                    .filter(k => k !== TIME_COLUMN && !aggregators[k])
                     .map(k => ({
                       name: k,
                       type: String(inputData.columns![k].type || 'string').toLowerCase(),
@@ -1455,7 +1456,7 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
             let possibleTimestampSpec: TimestampSpec;
             if (isDruidSource(spec)) {
               possibleTimestampSpec = {
-                column: '__time',
+                column: TIME_COLUMN,
                 format: 'auto',
               };
             } else {
@@ -1608,7 +1609,7 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
         data: {
           headerAndRows: headerAndRowsFromSampleResponse({
             sampleResponse,
-            columnOrder: ['__time'].concat(inputFormatColumns),
+            columnOrder: [TIME_COLUMN].concat(inputFormatColumns),
           }),
           spec,
         },
@@ -1802,7 +1803,7 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
       transformQueryState: new QueryState({
         data: headerAndRowsFromSampleResponse({
           sampleResponse,
-          columnOrder: ['__time'].concat(inputFormatColumns),
+          columnOrder: [TIME_COLUMN].concat(inputFormatColumns),
         }),
         lastData: transformQueryState.getSomeData(),
       }),
@@ -2020,7 +2021,7 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
         filterQueryState: new QueryState({
           data: headerAndRowsFromSampleResponse({
             sampleResponse,
-            columnOrder: ['__time'].concat(inputFormatColumns),
+            columnOrder: [TIME_COLUMN].concat(inputFormatColumns),
             parsedOnly: true,
           }),
           lastData: filterQueryState.getSomeData(),
@@ -2043,7 +2044,7 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
 
     const headerAndRowsNoFilter = headerAndRowsFromSampleResponse({
       sampleResponse: sampleResponseNoFilter,
-      columnOrder: ['__time'].concat(inputFormatColumns),
+      columnOrder: [TIME_COLUMN].concat(inputFormatColumns),
       parsedOnly: true,
     });
 
@@ -2232,7 +2233,9 @@ export class LoadDataView extends React.PureComponent<LoadDataViewProps, LoadDat
         data: {
           headerAndRows: headerAndRowsFromSampleResponse({
             sampleResponse,
-            columnOrder: ['__time'].concat(dimensions ? dimensions.map(getDimensionSpecName) : []),
+            columnOrder: [TIME_COLUMN].concat(
+              dimensions ? dimensions.map(getDimensionSpecName) : [],
+            ),
             suffixColumnOrder: metricsSpec ? metricsSpec.map(getMetricSpecName) : undefined,
           }),
           dimensions,
diff --git a/website/.spelling b/website/.spelling
index f89b29a578f6..3a85dc6ad361 100644
--- a/website/.spelling
+++ b/website/.spelling
@@ -1038,6 +1038,7 @@ baseDir
 chatHandlerNumRetries
 chatHandlerTimeout
 connectorConfig
+countryName
 dataSchema's
 foldCase
 forceGuaranteedRollup
@@ -1782,6 +1783,7 @@ successfulSending
 taskBlackListCleanupPeriod
 tasklogs
 timeBoundary
+timestampSpec
 tmp
 tmpfs
 truststore