[core] Support creating Iceberg metadata based on old ones

paimon-core/src/main/java/org/apache/paimon/iceberg/AppendOnlyIcebergCommitCallback.java

@@ -0,0 +1,35 @@
+/*
+ * 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.iceberg;
+
+import org.apache.paimon.io.DataFileMeta;
+import org.apache.paimon.table.FileStoreTable;
+
+/** {@link AbstractIcebergCommitCallback} for append only tables. */
+public class AppendOnlyIcebergCommitCallback extends AbstractIcebergCommitCallback {
+
+    public AppendOnlyIcebergCommitCallback(FileStoreTable table, String commitUser) {
+        super(table, commitUser);
+    }
+
+    @Override
+    protected boolean shouldAddFileToIceberg(DataFileMeta meta) {
+        return true;
+    }
+}

paimon-core/src/main/java/org/apache/paimon/iceberg/PrimaryKeyIcebergCommitCallback.java

@@ -0,0 +1,36 @@
+/*
+ * 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.iceberg;
+
+import org.apache.paimon.io.DataFileMeta;
+import org.apache.paimon.table.FileStoreTable;
+
+/** {@link AbstractIcebergCommitCallback} for primary key tables. */
+public class PrimaryKeyIcebergCommitCallback extends AbstractIcebergCommitCallback {
+
+    public PrimaryKeyIcebergCommitCallback(FileStoreTable table, String commitUser) {
+        super(table, commitUser);
+    }
+
+    @Override
+    protected boolean shouldAddFileToIceberg(DataFileMeta meta) {
+        int maxLevel = table.coreOptions().numLevels() - 1;
+        return meta.level() == maxLevel;
+    }
+}

paimon-core/src/main/java/org/apache/paimon/iceberg/manifest/IcebergConversions.java

@@ -18,13 +18,16 @@
 
 package org.apache.paimon.iceberg.manifest;
 
+import org.apache.paimon.data.BinaryString;
 import org.apache.paimon.data.Decimal;
 import org.apache.paimon.types.DataType;
+import org.apache.paimon.types.DecimalType;
 
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.CharBuffer;
 import java.nio.charset.CharacterCodingException;
+import java.nio.charset.CharsetDecoder;
 import java.nio.charset.CharsetEncoder;
 import java.nio.charset.StandardCharsets;
 
@@ -40,6 +43,8 @@ private IcebergConversions() {}
 
     private static final ThreadLocal<CharsetEncoder> ENCODER =
             ThreadLocal.withInitial(StandardCharsets.UTF_8::newEncoder);
+    private static final ThreadLocal<CharsetDecoder> DECODER =
+            ThreadLocal.withInitial(StandardCharsets.UTF_8::newDecoder);
 
     public static ByteBuffer toByteBuffer(DataType type, Object value) {
         switch (type.getTypeRoot()) {
@@ -78,4 +83,37 @@ public static ByteBuffer toByteBuffer(DataType type, Object value) {
                 throw new UnsupportedOperationException("Cannot serialize type: " + type);
         }
     }
+
+    public static Object toPaimonObject(DataType type, byte[] bytes) {
+        switch (type.getTypeRoot()) {
+            case BOOLEAN:
+                return bytes[0] != 0;
+            case INTEGER:
+            case DATE:
+                return ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).getInt();
+            case BIGINT:
+                return ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).getLong();
+            case FLOAT:
+                return ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).getFloat();
+            case DOUBLE:
+                return ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).getDouble();
+            case CHAR:
+            case VARCHAR:
+                try {
+                    return BinaryString.fromString(
+                            DECODER.get().decode(ByteBuffer.wrap(bytes)).toString());
+                } catch (CharacterCodingException e) {
+                    throw new RuntimeException("Failed to decode bytes as UTF-8", e);
+                }
+            case BINARY:
+            case VARBINARY:
+                return bytes;
+            case DECIMAL:
+                DecimalType decimalType = (DecimalType) type;
+                return Decimal.fromUnscaledBytes(
+                        bytes, decimalType.getPrecision(), decimalType.getScale());
+            default:
+                throw new UnsupportedOperationException("Cannot deserialize type: " + type);
+        }
+    }
 }