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Merged
JingsongLi merged 2 commits into from
Jan 7, 2025
Merged

[core] Introduce nested type cast to string #4848

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Zouxxyy Jan 6, 2025
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Zouxxyy Jan 6, 2025
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70 changes: 70 additions & 0 deletions paimon-common/src/main/java/org/apache/paimon/casting/ArrayToStringCastRule.java
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@@ -0,0 +1,70 @@
/*
* 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.paimon.casting;

import org.apache.paimon.data.BinaryString;
import org.apache.paimon.data.InternalArray;
import org.apache.paimon.types.ArrayType;
import org.apache.paimon.types.DataType;
import org.apache.paimon.types.DataTypeFamily;
import org.apache.paimon.types.DataTypeRoot;
import org.apache.paimon.types.VarCharType;

/** {@link DataTypeRoot#ARRAY} to {@link DataTypeFamily#CHARACTER_STRING} cast rule. */
public class ArrayToStringCastRule extends AbstractCastRule<InternalArray, BinaryString> {

static final ArrayToStringCastRule INSTANCE = new ArrayToStringCastRule();

private ArrayToStringCastRule() {
super(
CastRulePredicate.builder()
.input(DataTypeRoot.ARRAY)
.target(DataTypeFamily.CHARACTER_STRING)
.build());
}

@Override
public CastExecutor<InternalArray, BinaryString> create(
DataType inputType, DataType targetType) {
ArrayType arrayType = (ArrayType) inputType;
InternalArray.ElementGetter elementGetter =
InternalArray.createElementGetter(arrayType.getElementType());
CastExecutor castExecutor =
CastExecutors.resolve(arrayType.getElementType(), VarCharType.STRING_TYPE);

return arrayData -> {
int size = arrayData.size();
StringBuilder sb = new StringBuilder();
sb.append("[");
for (int i = 0; i < size; i++) {
Object o = elementGetter.getElementOrNull(arrayData, i);
if (o == null) {
sb.append("null");
} else {
sb.append(castExecutor.cast(o));
}
if (i != size - 1) {
sb.append(", ");
}
}
sb.append("]");
return BinaryString.fromString(sb.toString());
};
}
}
3 changes: 3 additions & 0 deletions paimon-common/src/main/java/org/apache/paimon/casting/CastExecutors.java
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Expand Up @@ -58,6 +58,9 @@ public class CastExecutors {
.addRule(TimeToStringCastRule.INSTANCE)
.addRule(DateToStringCastRule.INSTANCE)
.addRule(StringToStringCastRule.INSTANCE)
.addRule(ArrayToStringCastRule.INSTANCE)
.addRule(MapToStringCastRule.INSTANCE)
.addRule(RowToStringCastRule.INSTANCE)
// From string rules
.addRule(StringToBooleanCastRule.INSTANCE)
.addRule(StringToDecimalCastRule.INSTANCE)
Expand Down
83 changes: 83 additions & 0 deletions paimon-common/src/main/java/org/apache/paimon/casting/MapToStringCastRule.java
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/*
* 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.paimon.casting;

import org.apache.paimon.data.BinaryString;
import org.apache.paimon.data.InternalArray;
import org.apache.paimon.data.InternalMap;
import org.apache.paimon.types.DataType;
import org.apache.paimon.types.DataTypeFamily;
import org.apache.paimon.types.DataTypeRoot;
import org.apache.paimon.types.MapType;
import org.apache.paimon.types.VarCharType;

/** {@link DataTypeRoot#MAP} to {@link DataTypeFamily#CHARACTER_STRING} cast rule. */
public class MapToStringCastRule extends AbstractCastRule<InternalMap, BinaryString> {

static final MapToStringCastRule INSTANCE = new MapToStringCastRule();

private MapToStringCastRule() {
super(
CastRulePredicate.builder()
.input(DataTypeRoot.MAP)
.target(DataTypeFamily.CHARACTER_STRING)
.build());
}

@Override
public CastExecutor<InternalMap, BinaryString> create(DataType inputType, DataType targetType) {
MapType mapType = (MapType) inputType;
InternalArray.ElementGetter keyGetter =
InternalArray.createElementGetter(mapType.getKeyType());
InternalArray.ElementGetter valueGetter =
InternalArray.createElementGetter(mapType.getValueType());
CastExecutor keyCastExecutor =
CastExecutors.resolve(mapType.getKeyType(), VarCharType.STRING_TYPE);
CastExecutor valueCastExecutor =
CastExecutors.resolve(mapType.getValueType(), VarCharType.STRING_TYPE);

return mapData -> {
InternalArray keyArray = mapData.keyArray();
InternalArray valueArray = mapData.valueArray();
int size = mapData.size();
StringBuilder sb = new StringBuilder();
sb.append("{");
for (int i = 0; i < size; i++) {
Object k = keyGetter.getElementOrNull(keyArray, i);
if (k == null) {
sb.append("null");
} else {
sb.append(keyCastExecutor.cast(k));
}
sb.append(" -> ");
Object v = valueGetter.getElementOrNull(valueArray, i);
if (v == null) {
sb.append("null");
} else {
sb.append(valueCastExecutor.cast(v));
}
if (i != size - 1) {
sb.append(", ");
}
}
sb.append("}");
return BinaryString.fromString(sb.toString());
};
}
}
73 changes: 73 additions & 0 deletions paimon-common/src/main/java/org/apache/paimon/casting/RowToStringCastRule.java
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/*
* 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.paimon.casting;

import org.apache.paimon.data.BinaryString;
import org.apache.paimon.data.InternalRow;
import org.apache.paimon.types.DataType;
import org.apache.paimon.types.DataTypeFamily;
import org.apache.paimon.types.DataTypeRoot;
import org.apache.paimon.types.RowType;
import org.apache.paimon.types.VarCharType;
import org.apache.paimon.utils.InternalRowUtils;

/** {@link DataTypeRoot#ROW} to {@link DataTypeFamily#CHARACTER_STRING} cast rule. */
public class RowToStringCastRule extends AbstractCastRule<InternalRow, BinaryString> {

static final RowToStringCastRule INSTANCE = new RowToStringCastRule();

private RowToStringCastRule() {
super(
CastRulePredicate.builder()
.input(DataTypeRoot.ROW)
.target(DataTypeFamily.CHARACTER_STRING)
.build());
}

@Override
public CastExecutor<InternalRow, BinaryString> create(DataType inputType, DataType targetType) {
RowType rowType = (RowType) inputType;
int fieldCount = rowType.getFieldCount();
InternalRow.FieldGetter[] fieldGetters = new InternalRow.FieldGetter[fieldCount];
CastExecutor[] castExecutors = new CastExecutor[fieldCount];
for (int i = 0; i < rowType.getFieldCount(); i++) {
DataType fieldType = rowType.getTypeAt(i);
fieldGetters[i] = InternalRowUtils.createNullCheckingFieldGetter(fieldType, i);
castExecutors[i] = CastExecutors.resolve(fieldType, VarCharType.STRING_TYPE);
}

return rowDate -> {
StringBuilder sb = new StringBuilder();
sb.append("{");
for (int i = 0; i < fieldCount; i++) {
Object field = fieldGetters[i].getFieldOrNull(rowDate);
if (field == null) {
sb.append("null");
} else {
sb.append(castExecutors[i].cast(field).toString());
}
if (i != fieldCount - 1) {
sb.append(", ");
}
}
sb.append("}");
return BinaryString.fromString(sb.toString());
};
}
}
68 changes: 68 additions & 0 deletions paimon-common/src/test/java/org/apache/paimon/casting/CastExecutorTest.java
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Expand Up @@ -19,17 +19,24 @@
package org.apache.paimon.casting;

import org.apache.paimon.data.BinaryString;
import org.apache.paimon.data.GenericArray;
import org.apache.paimon.data.GenericMap;
import org.apache.paimon.data.GenericRow;
import org.apache.paimon.data.Timestamp;
import org.apache.paimon.types.ArrayType;
import org.apache.paimon.types.BigIntType;
import org.apache.paimon.types.BinaryType;
import org.apache.paimon.types.BooleanType;
import org.apache.paimon.types.CharType;
import org.apache.paimon.types.DataTypes;
import org.apache.paimon.types.DateType;
import org.apache.paimon.types.DecimalType;
import org.apache.paimon.types.DoubleType;
import org.apache.paimon.types.FloatType;
import org.apache.paimon.types.IntType;
import org.apache.paimon.types.LocalZonedTimestampType;
import org.apache.paimon.types.MapType;
import org.apache.paimon.types.RowType;
import org.apache.paimon.types.SmallIntType;
import org.apache.paimon.types.TimeType;
import org.apache.paimon.types.TimestampType;
Expand All @@ -41,6 +48,8 @@

import org.junit.jupiter.api.Test;

import java.util.HashMap;
import java.util.Map;
import java.util.TimeZone;

import static org.assertj.core.api.Assertions.assertThat;
Expand Down Expand Up @@ -681,6 +690,65 @@ public void testTimeToTimestamp() {
DateTimeUtils.parseTimestampData("1970-01-01 " + time, 3));
}

@Test
public void testArrayToString() {
ArrayType arrayType = new ArrayType(DataTypes.INT());
GenericArray genericArray = new GenericArray(new Integer[] {1, null, 2});
compareCastResult(
CastExecutors.resolve(arrayType, DataTypes.STRING()),
genericArray,
BinaryString.fromString("[1, null, 2]"));
}

@Test
public void testMapToString() {
MapType mapType = new MapType(DataTypes.INT(), DataTypes.STRING());
Map<Object, Object> javaMap = new HashMap<>();
javaMap.put(1, BinaryString.fromString("i"));
javaMap.put(2, BinaryString.fromString("miss"));
javaMap.put(3, BinaryString.fromString("you"));
javaMap.put(4, null);
GenericMap genericMap = new GenericMap(javaMap);
compareCastResult(
CastExecutors.resolve(mapType, DataTypes.STRING()),
genericMap,
BinaryString.fromString("{1 -> i, 2 -> miss, 3 -> you, 4 -> null}"));
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@JingsongLi JingsongLi Jan 7, 2025 •
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Is this from Spark SQL? (Why not using {a=1, b=1}), please check SQL engines.

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@Zouxxyy Zouxxyy Jan 7, 2025 •
edited
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yes, copy from spark, see https://issues.apache.org/jira/browse/SPARK-32499

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@JingsongLi JingsongLi Jan 7, 2025

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No for show, you should take a look to Spark SQL.

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@Zouxxyy Zouxxyy Jan 7, 2025

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This is the behavior of Spark SQL's cast.

select cast (struct(1, 'a') as string), cast (map(1, 'a') as string), cast (array(1,2,3) as string)
+----------------------------+-------------------------+------------------------------+
|CAST(struct(1, a) AS STRING)|CAST(map(1, a) AS STRING)|CAST(array(1, 2, 3) AS STRING)|
+----------------------------+-------------------------+------------------------------+
|                      {1, a}|                 {1 -> a}|                     [1, 2, 3]|
+----------------------------+-------------------------+------------------------------+

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Can you take a look to other engines? For example, trino and snowflake.

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@Zouxxyy Zouxxyy Jan 7, 2025

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Here are some examples from other engines, I did not find examples of Snowflake.

Flink

select cast (row(1, 'a') as string), cast(map[1, 'a'] as string), cast (array[1,2,3] as string);

-- | -- | --
(1,a) | {1=a} | [1, 2, 3]

Spark

spark-sql> select cast (struct(1, 'a') as string), cast (map(1, 'a') as string), cast (array(1,2,3) as string);

+----------------------------+-------------------------+------------------------------+
|CAST(struct(1, a) AS STRING)|CAST(map(1, a) AS STRING)|CAST(array(1, 2, 3) AS STRING)|
+----------------------------+-------------------------+------------------------------+
|                      {1, a}|                 {1 -> a}|                     [1, 2, 3]|
+----------------------------+-------------------------+------------------------------+

Trino (can't cast, just show)

trino> select row(1, 'a'), map(ARRAY[1], ARRAY['a']), array[1,2,3];

 _col0  | _col1 |   _col2   
--------+-------+-----------
 {1, a} | {1=a} | [1, 2, 3]

StarRocks (can't cast, just show)

select row(1, 'a'), map(1, 'a'), [1, 2, 3];

{"col1":1,"col2":"a"} | {1:"a"} | [1,2,3]

}

@Test
public void testRowToString() {
RowType rowType =
DataTypes.ROW(
DataTypes.FIELD(0, "f0", DataTypes.INT()),
DataTypes.FIELD(
1,
"f1",
DataTypes.ROW(
DataTypes.FIELD(2, "f0", DataTypes.DATE()),
DataTypes.FIELD(
3,
"f1",
new MapType(
DataTypes.INT(),
new ArrayType(DataTypes.INT()))),
DataTypes.FIELD(4, "f2", DataTypes.INT()))));

HashMap<Integer, GenericArray> javaMap = new HashMap<>();
javaMap.put(1, new GenericArray(new Integer[] {1, null, 2}));
GenericRow row =
GenericRow.of(
1,
GenericRow.of(
DateTimeUtils.parseDate("2025-01-06"),
new GenericMap(javaMap),
null));

compareCastResult(
CastExecutors.resolve(rowType, DataTypes.STRING()),
row,
BinaryString.fromString("{1, {2025-01-06, {1 -> [1, null, 2]}, null}}"));
}

@SuppressWarnings("rawtypes")
private void compareCastResult(CastExecutor<?, ?> cast, Object input, Object output) {
assertThat(((CastExecutor) cast).cast(input)).isEqualTo(output);
Expand Down
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