[GitHub] [iceberg] stevenzwu commented on a change in pull request #2731: Flink: Project the RowData from DeleteFilter to remove meta-columns.

[GitBox <gi...@apache.org>]

stevenzwu commented on a change in pull request #2731:
URL: https://github.com/apache/iceberg/pull/2731#discussion_r669313152



##########
File path: flink/src/main/java/org/apache/iceberg/flink/data/RowDataProjection.java
##########
@@ -0,0 +1,85 @@
+/*
+ * 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.iceberg.flink.data;
+
+import org.apache.flink.table.data.GenericRowData;
+import org.apache.flink.table.data.RowData;
+import org.apache.flink.table.types.logical.RowType;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.flink.FlinkSchemaUtil;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.types.Types;
+
+public class RowDataProjection {
+  private final RowData.FieldGetter[] getters;
+
+  public static RowDataProjection create(Schema schema, Schema projectSchema) {
+    return new RowDataProjection(FlinkSchemaUtil.convert(schema), schema.asStruct(), projectSchema.asStruct());
+  }
+
+  private RowDataProjection(RowType rowType, Types.StructType rowStruct, Types.StructType projectType) {
+    this.getters = new RowData.FieldGetter[projectType.fields().size()];
+    for (int i = 0; i < getters.length; i++) {
+      getters[i] = createFieldGetter(rowType, rowStruct, projectType.fields().get(i));
+    }
+  }
+
+  private static RowData.FieldGetter createFieldGetter(RowType rowType,
+                                                       Types.StructType rowStruct,
+                                                       Types.NestedField projectField) {
+    for (int i = 0; i < rowStruct.fields().size(); i++) {
+      Types.NestedField rowField = rowStruct.fields().get(i);
+      if (rowField.fieldId() == projectField.fieldId()) {
+        Preconditions.checkArgument(rowField.type().typeId() == projectField.type().typeId(),
+            String.format("Different iceberg type between row field <%s> and project field <%s>",
+                rowField, projectField));
+
+        switch (projectField.type().typeId()) {
+          case STRUCT:
+            RowType nestedRowType = (RowType) rowType.getTypeAt(i);
+            int rowPos = i;
+            return row -> {
+              RowData nestedRow = row.isNullAt(rowPos) ? null : row.getRow(rowPos, nestedRowType.getFieldCount());
+              return new RowDataProjection(nestedRowType, rowField.type().asStructType(),
+                  projectField.type().asStructType()).project(nestedRow);
+            };
+
+          case MAP:
+          case LIST:
+            throw new IllegalArgumentException(String.format("Cannot project list or map field: %s", projectField));
+          default:
+            return RowData.createFieldGetter(rowType.getTypeAt(i), i);
+        }
+      }
+    }
+    throw new IllegalArgumentException(String.format("Cannot find field %s in %s", projectField, rowStruct));
+  }
+
+  public RowData project(RowData row) {
+    GenericRowData projectedRow = new GenericRowData(getters.length);

Review comment:
       RowDataIterator reuses object. this change deviates from that model and creates a copy for each row




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