aokolnychyi commented on code in PR #9841:
URL: https://github.com/apache/iceberg/pull/9841#discussion_r1566673808


##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/comet/CometIcebergColumnReader.java:
##########
@@ -0,0 +1,164 @@
+/*
+ * 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.spark.data.vectorized.comet;
+
+import java.io.IOException;
+import java.util.Map;
+import org.apache.comet.parquet.AbstractColumnReader;
+import org.apache.comet.parquet.ColumnReader;
+import org.apache.comet.parquet.TypeUtil;
+import org.apache.comet.parquet.Utils;
+import org.apache.comet.vector.CometVector;
+import org.apache.iceberg.parquet.VectorizedReader;
+import org.apache.iceberg.spark.SparkSchemaUtil;
+import org.apache.iceberg.types.Types;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.column.page.PageReader;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.hadoop.metadata.ColumnPath;
+import org.apache.spark.sql.types.DataType;
+import org.apache.spark.sql.types.Metadata;
+import org.apache.spark.sql.types.StructField;
+
+/**
+ * A Iceberg Parquet column reader backed by a Boson {@link ColumnReader}. 
This class should be used
+ * together with {@link CometIcebergVector}.
+ *
+ * <p>Example:
+ *
+ * <pre>
+ *   BosonIcebergColumnReader reader = ...
+ *   reader.setBatchSize(batchSize);
+ *
+ *   while (hasMoreRowsToRead) {
+ *     if (endOfRowGroup) {
+ *       reader.reset();
+ *       PageReader pageReader = ...
+ *       reader.setPageReader(pageReader);
+ *     }
+ *
+ *     int numRows = ...
+ *     BosonIcebergVector vector = reader.read(null, numRows);
+ *
+ *     // consume the vector
+ *   }
+ *
+ *   reader.close();
+ * </pre>
+ */
+@SuppressWarnings("checkstyle:VisibilityModifier")
+public class CometIcebergColumnReader implements 
VectorizedReader<CometIcebergVector> {
+  public static final int DEFAULT_BATCH_SIZE = 5000;
+
+  private final DataType sparkType;
+  protected AbstractColumnReader delegate;

Review Comment:
   Will it be part of the Comet library?



##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/comet/CometIcebergColumnarBatchReader.java:
##########
@@ -0,0 +1,303 @@
+/*
+ * 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.spark.data.vectorized.comet;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import org.apache.comet.parquet.AbstractColumnReader;
+import org.apache.comet.parquet.BatchReader;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.data.DeleteFilter;
+import org.apache.iceberg.deletes.PositionDeleteIndex;
+import org.apache.iceberg.parquet.VectorizedReader;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.spark.SparkSchemaUtil;
+import org.apache.iceberg.util.Pair;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.hadoop.metadata.ColumnPath;
+import org.apache.spark.sql.catalyst.InternalRow;
+import org.apache.spark.sql.vectorized.ColumnVector;
+import org.apache.spark.sql.vectorized.ColumnarBatch;
+
+/**
+ * {@link VectorizedReader} that returns Spark's {@link ColumnarBatch} to 
support Spark's vectorized
+ * read path. The {@link ColumnarBatch} returned is created by passing in the 
Arrow vectors
+ * populated via delegated read calls to {@linkplain CometIcebergColumnReader 
VectorReader(s)}.
+ */
+@SuppressWarnings("checkstyle:VisibilityModifier")
+public class CometIcebergColumnarBatchReader implements 
VectorizedReader<ColumnarBatch> {
+
+  private final CometIcebergColumnReader[] readers;
+  private final boolean hasIsDeletedColumn;
+  private DeleteFilter<InternalRow> deletes = null;
+  private long rowStartPosInBatch = 0;
+  private final BatchReader delegate;
+
+  public CometIcebergColumnarBatchReader(List<VectorizedReader<?>> readers, 
Schema schema) {
+    this.readers =
+        readers.stream()
+            .map(CometIcebergColumnReader.class::cast)
+            .toArray(CometIcebergColumnReader[]::new);
+    this.hasIsDeletedColumn =
+        readers.stream().anyMatch(reader -> reader instanceof 
CometIcebergDeleteColumnReader);
+
+    AbstractColumnReader[] abstractColumnReaders = new 
AbstractColumnReader[readers.size()];
+    delegate = new BatchReader(abstractColumnReaders);
+    delegate.setSparkSchema(SparkSchemaUtil.convert(schema));
+  }
+
+  @Override
+  public void setRowGroupInfo(
+      PageReadStore pageStore, Map<ColumnPath, ColumnChunkMetaData> metaData, 
long rowPosition) {
+    for (int i = 0; i < readers.length; i++) {
+      try {
+        if (!(readers[i] instanceof CometIcebergConstantColumnReader)
+            && !(readers[i] instanceof CometIcebergPositionColumnReader)
+            && !(readers[i] instanceof CometIcebergDeleteColumnReader)) {
+          readers[i].reset();
+          readers[i].setPageReader(
+              pageStore.getPageReader(((CometIcebergColumnReader) 
readers[i]).getDescriptor()));
+        }
+      } catch (IOException e) {
+        throw new UncheckedIOException("Failed to setRowGroupInfo for Comet 
vectorization", e);
+      }
+    }
+
+    for (int i = 0; i < readers.length; i++) {
+      delegate.getColumnReaders()[i] = ((CometIcebergColumnReader) 
this.readers[i]).getDelegate();
+    }
+
+    this.rowStartPosInBatch = rowPosition;
+  }
+
+  public void setDeleteFilter(DeleteFilter<InternalRow> deleteFilter) {
+    this.deletes = deleteFilter;
+  }
+
+  @Override
+  public final ColumnarBatch read(ColumnarBatch reuse, int numRowsToRead) {
+    ColumnarBatch columnarBatch = new 
ColumnBatchLoader(numRowsToRead).loadDataToColumnBatch();
+    rowStartPosInBatch += numRowsToRead;
+    return columnarBatch;
+  }
+
+  @Override
+  public void setBatchSize(int batchSize) {
+    for (CometIcebergColumnReader reader : readers) {
+      if (reader != null) {
+        reader.setBatchSize(batchSize);
+      }
+    }
+  }
+
+  @Override
+  public void close() {
+    for (CometIcebergColumnReader reader : readers) {
+      if (reader != null) {
+        reader.close();
+      }
+    }
+  }
+
+  private class ColumnBatchLoader {
+    private final int numRowsToRead;
+    // the rowId mapping to skip deleted rows for all column vectors inside a 
batch, it is null when
+    // there is no deletes
+    private int[] rowIdMapping;
+    // the array to indicate if a row is deleted or not, it is null when there 
is no "_deleted"
+    // metadata column
+    private boolean[] isDeleted;
+
+    ColumnBatchLoader(int numRowsToRead) {
+      Preconditions.checkArgument(
+          numRowsToRead > 0, "Invalid number of rows to read: %s", 
numRowsToRead);
+      this.numRowsToRead = numRowsToRead;
+      if (hasIsDeletedColumn) {
+        isDeleted = new boolean[numRowsToRead];
+      }
+    }
+
+    ColumnarBatch loadDataToColumnBatch() {

Review Comment:
   How much of this overlaps with `ColumnarBatchReader`?



##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/comet/CometIcebergColumnarBatchReader.java:
##########
@@ -0,0 +1,303 @@
+/*
+ * 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.spark.data.vectorized.comet;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import org.apache.comet.parquet.AbstractColumnReader;
+import org.apache.comet.parquet.BatchReader;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.data.DeleteFilter;
+import org.apache.iceberg.deletes.PositionDeleteIndex;
+import org.apache.iceberg.parquet.VectorizedReader;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.spark.SparkSchemaUtil;
+import org.apache.iceberg.util.Pair;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.hadoop.metadata.ColumnPath;
+import org.apache.spark.sql.catalyst.InternalRow;
+import org.apache.spark.sql.vectorized.ColumnVector;
+import org.apache.spark.sql.vectorized.ColumnarBatch;
+
+/**
+ * {@link VectorizedReader} that returns Spark's {@link ColumnarBatch} to 
support Spark's vectorized
+ * read path. The {@link ColumnarBatch} returned is created by passing in the 
Arrow vectors
+ * populated via delegated read calls to {@linkplain CometIcebergColumnReader 
VectorReader(s)}.
+ */
+@SuppressWarnings("checkstyle:VisibilityModifier")
+public class CometIcebergColumnarBatchReader implements 
VectorizedReader<ColumnarBatch> {

Review Comment:
   Same here, no need for Iceberg in the name.



##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/comet/CometIcebergPositionColumnReader.java:
##########
@@ -0,0 +1,62 @@
+/*
+ * 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.spark.data.vectorized.comet;
+
+import org.apache.comet.parquet.MetadataColumnReader;
+import org.apache.comet.parquet.Native;
+import org.apache.iceberg.types.Types;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.spark.sql.types.DataTypes;
+
+public class CometIcebergPositionColumnReader extends CometIcebergColumnReader 
{

Review Comment:
   Do all of these classes have to be public?



##########
spark/v3.4/build.gradle:
##########
@@ -70,8 +70,11 @@ 
project(":iceberg-spark:iceberg-spark-${sparkMajorVersion}_${scalaVersion}") {
       exclude group: 'io.netty', module: 'netty-buffer'
       exclude group: 'io.netty', module: 'netty-common'
       exclude group: 'org.roaringbitmap'
+      exclude group: 'org.apache.comet'
     }
 
+    compileOnly 
"org.apache.comet:comet-spark-spark${sparkMajorVersion}_${scalaVersion}:0.1.0-SNAPSHOT"

Review Comment:
   I assume this library will only contain the reader, not the operators.



##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/comet/CometIcebergColumnReader.java:
##########
@@ -0,0 +1,164 @@
+/*
+ * 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.spark.data.vectorized.comet;
+
+import java.io.IOException;
+import java.util.Map;
+import org.apache.comet.parquet.AbstractColumnReader;
+import org.apache.comet.parquet.ColumnReader;
+import org.apache.comet.parquet.TypeUtil;
+import org.apache.comet.parquet.Utils;
+import org.apache.comet.vector.CometVector;
+import org.apache.iceberg.parquet.VectorizedReader;
+import org.apache.iceberg.spark.SparkSchemaUtil;
+import org.apache.iceberg.types.Types;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.column.page.PageReader;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.hadoop.metadata.ColumnPath;
+import org.apache.spark.sql.types.DataType;
+import org.apache.spark.sql.types.Metadata;
+import org.apache.spark.sql.types.StructField;
+
+/**
+ * A Iceberg Parquet column reader backed by a Boson {@link ColumnReader}. 
This class should be used
+ * together with {@link CometIcebergVector}.
+ *
+ * <p>Example:
+ *
+ * <pre>
+ *   BosonIcebergColumnReader reader = ...
+ *   reader.setBatchSize(batchSize);
+ *
+ *   while (hasMoreRowsToRead) {
+ *     if (endOfRowGroup) {
+ *       reader.reset();
+ *       PageReader pageReader = ...
+ *       reader.setPageReader(pageReader);
+ *     }
+ *
+ *     int numRows = ...
+ *     BosonIcebergVector vector = reader.read(null, numRows);
+ *
+ *     // consume the vector
+ *   }
+ *
+ *   reader.close();
+ * </pre>
+ */
+@SuppressWarnings("checkstyle:VisibilityModifier")
+public class CometIcebergColumnReader implements 
VectorizedReader<CometIcebergVector> {

Review Comment:
   I'd just call it `CometColumnReader`. No need for Iceberg in the name.



##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/VectorizedSparkParquetReaders.java:
##########
@@ -51,22 +53,43 @@ public class VectorizedSparkParquetReaders {
 
   private VectorizedSparkParquetReaders() {}
 
-  public static ColumnarBatchReader buildReader(
+  public static VectorizedReader buildReader(
       Schema expectedSchema,
       MessageType fileSchema,
       Map<Integer, ?> idToConstant,
       DeleteFilter<InternalRow> deleteFilter) {
-    return (ColumnarBatchReader)
-        TypeWithSchemaVisitor.visit(
-            expectedSchema.asStruct(),
-            fileSchema,
-            new ReaderBuilder(
-                expectedSchema,
-                fileSchema,
-                NullCheckingForGet.NULL_CHECKING_ENABLED,
-                idToConstant,
-                ColumnarBatchReader::new,
-                deleteFilter));
+    boolean hasCometJar = false;
+    try {

Review Comment:
   I would **_consider_** the following mechanism for controlling Comet (just a 
thought):
   - Add an enum called `ReaderType` (or a similar name) with two values: 
`ICEBERG` and `COMET`.
   - Add a new property to `SparkSQLProperties` that would control which reader 
to use.
     - Something like `spark.sql.iceberg.parquet.reader-type`.
   - Parse the SQL conf in `SparkBatch` and pass the reader type to 
`SparkColumnarReaderFactory`.
   - Propagate the reader type to `BaseBatchReader`.
   - Add a new method `buildCometReader` to `VectorizedSparkParquetReaders`.
     - I don't think we should use Comet depending on whether the jar is there.
   - Chose either `buildReader` or `buildCometReader` based on the reader type 
in `newParquetIterable`.



##########
spark/v3.4/spark/src/main/java/org/apache/iceberg/spark/data/vectorized/comet/CometIcebergColumnarBatchReader.java:
##########
@@ -0,0 +1,303 @@
+/*
+ * 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.spark.data.vectorized.comet;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import org.apache.comet.parquet.AbstractColumnReader;
+import org.apache.comet.parquet.BatchReader;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.data.DeleteFilter;
+import org.apache.iceberg.deletes.PositionDeleteIndex;
+import org.apache.iceberg.parquet.VectorizedReader;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.spark.SparkSchemaUtil;
+import org.apache.iceberg.util.Pair;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.hadoop.metadata.ColumnPath;
+import org.apache.spark.sql.catalyst.InternalRow;
+import org.apache.spark.sql.vectorized.ColumnVector;
+import org.apache.spark.sql.vectorized.ColumnarBatch;
+
+/**
+ * {@link VectorizedReader} that returns Spark's {@link ColumnarBatch} to 
support Spark's vectorized
+ * read path. The {@link ColumnarBatch} returned is created by passing in the 
Arrow vectors
+ * populated via delegated read calls to {@linkplain CometIcebergColumnReader 
VectorReader(s)}.
+ */
+@SuppressWarnings("checkstyle:VisibilityModifier")
+public class CometIcebergColumnarBatchReader implements 
VectorizedReader<ColumnarBatch> {
+
+  private final CometIcebergColumnReader[] readers;
+  private final boolean hasIsDeletedColumn;
+  private DeleteFilter<InternalRow> deletes = null;
+  private long rowStartPosInBatch = 0;
+  private final BatchReader delegate;
+
+  public CometIcebergColumnarBatchReader(List<VectorizedReader<?>> readers, 
Schema schema) {
+    this.readers =
+        readers.stream()
+            .map(CometIcebergColumnReader.class::cast)
+            .toArray(CometIcebergColumnReader[]::new);
+    this.hasIsDeletedColumn =
+        readers.stream().anyMatch(reader -> reader instanceof 
CometIcebergDeleteColumnReader);
+
+    AbstractColumnReader[] abstractColumnReaders = new 
AbstractColumnReader[readers.size()];
+    delegate = new BatchReader(abstractColumnReaders);
+    delegate.setSparkSchema(SparkSchemaUtil.convert(schema));
+  }
+
+  @Override
+  public void setRowGroupInfo(
+      PageReadStore pageStore, Map<ColumnPath, ColumnChunkMetaData> metaData, 
long rowPosition) {
+    for (int i = 0; i < readers.length; i++) {
+      try {
+        if (!(readers[i] instanceof CometIcebergConstantColumnReader)
+            && !(readers[i] instanceof CometIcebergPositionColumnReader)
+            && !(readers[i] instanceof CometIcebergDeleteColumnReader)) {
+          readers[i].reset();
+          readers[i].setPageReader(
+              pageStore.getPageReader(((CometIcebergColumnReader) 
readers[i]).getDescriptor()));
+        }
+      } catch (IOException e) {
+        throw new UncheckedIOException("Failed to setRowGroupInfo for Comet 
vectorization", e);
+      }
+    }
+
+    for (int i = 0; i < readers.length; i++) {
+      delegate.getColumnReaders()[i] = ((CometIcebergColumnReader) 
this.readers[i]).getDelegate();
+    }
+
+    this.rowStartPosInBatch = rowPosition;
+  }
+
+  public void setDeleteFilter(DeleteFilter<InternalRow> deleteFilter) {
+    this.deletes = deleteFilter;
+  }
+
+  @Override
+  public final ColumnarBatch read(ColumnarBatch reuse, int numRowsToRead) {
+    ColumnarBatch columnarBatch = new 
ColumnBatchLoader(numRowsToRead).loadDataToColumnBatch();
+    rowStartPosInBatch += numRowsToRead;
+    return columnarBatch;
+  }
+
+  @Override
+  public void setBatchSize(int batchSize) {
+    for (CometIcebergColumnReader reader : readers) {
+      if (reader != null) {
+        reader.setBatchSize(batchSize);
+      }
+    }
+  }
+
+  @Override
+  public void close() {
+    for (CometIcebergColumnReader reader : readers) {
+      if (reader != null) {
+        reader.close();
+      }
+    }
+  }
+
+  private class ColumnBatchLoader {
+    private final int numRowsToRead;
+    // the rowId mapping to skip deleted rows for all column vectors inside a 
batch, it is null when
+    // there is no deletes
+    private int[] rowIdMapping;
+    // the array to indicate if a row is deleted or not, it is null when there 
is no "_deleted"
+    // metadata column
+    private boolean[] isDeleted;
+
+    ColumnBatchLoader(int numRowsToRead) {
+      Preconditions.checkArgument(
+          numRowsToRead > 0, "Invalid number of rows to read: %s", 
numRowsToRead);
+      this.numRowsToRead = numRowsToRead;
+      if (hasIsDeletedColumn) {
+        isDeleted = new boolean[numRowsToRead];
+      }
+    }
+
+    ColumnarBatch loadDataToColumnBatch() {
+      int numRowsUndeleted = initRowIdMapping();
+
+      ColumnVector[] arrowColumnVectors = readDataToColumnVectors();
+
+      ColumnarBatch newColumnarBatch = new ColumnarBatch(arrowColumnVectors);
+      newColumnarBatch.setNumRows(numRowsUndeleted);
+
+      if (hasEqDeletes()) {
+        applyEqDelete(newColumnarBatch);
+      }
+
+      if (hasIsDeletedColumn && rowIdMapping != null) {
+        // reset the row id mapping array, so that it doesn't filter out the 
deleted rows
+        for (int i = 0; i < numRowsToRead; i++) {
+          rowIdMapping[i] = i;
+        }
+        newColumnarBatch.setNumRows(numRowsToRead);
+      }
+
+      if (hasIsDeletedColumn) {
+        readDeletedColumnIfNecessary(arrowColumnVectors);
+      }
+
+      return newColumnarBatch;
+    }
+
+    ColumnVector[] readDataToColumnVectors() {
+      ColumnVector[] columnVectors = new ColumnVector[readers.length];
+      // Fetch rows for all readers in the delegate
+      delegate.nextBatch(numRowsToRead);
+      for (int i = 0; i < readers.length; i++) {
+        CometIcebergVector bv = ((CometIcebergColumnReader) 
readers[i]).getVector();
+        bv.setDelegate(((CometIcebergColumnReader) 
readers[i]).getDelegate().currentBatch());
+        bv.setRowIdMapping(rowIdMapping);
+        columnVectors[i] = bv;
+      }
+
+      return columnVectors;
+    }
+
+    boolean hasEqDeletes() {
+      return deletes != null && deletes.hasEqDeletes();
+    }
+
+    int initRowIdMapping() {
+      Pair<int[], Integer> posDeleteRowIdMapping = posDelRowIdMapping();
+      if (posDeleteRowIdMapping != null) {
+        rowIdMapping = posDeleteRowIdMapping.first();
+        return posDeleteRowIdMapping.second();
+      } else {
+        rowIdMapping = initEqDeleteRowIdMapping();
+        return numRowsToRead;
+      }
+    }
+
+    Pair<int[], Integer> posDelRowIdMapping() {
+      if (deletes != null && deletes.hasPosDeletes()) {
+        return buildPosDelRowIdMapping(deletes.deletedRowPositions());
+      } else {
+        return null;
+      }
+    }
+
+    /**
+     * Build a row id mapping inside a batch, which skips deleted rows. Here 
is an example of how we
+     * delete 2 rows in a batch with 8 rows in total. [0,1,2,3,4,5,6,7] -- 
Original status of the
+     * row id mapping array [F,F,F,F,F,F,F,F] -- Original status of the 
isDeleted array Position
+     * delete 2, 6 [0,1,3,4,5,7,-,-] -- After applying position deletes [Set 
Num records to 6]
+     * [F,F,T,F,F,F,T,F] -- After applying position deletes
+     *
+     * @param deletedRowPositions a set of deleted row positions
+     * @return the mapping array and the new num of rows in a batch, null if 
no row is deleted
+     */
+    Pair<int[], Integer> buildPosDelRowIdMapping(PositionDeleteIndex 
deletedRowPositions) {

Review Comment:
   Same question about the overlap here.



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