FrankChen021 commented on code in PR #19510: URL: https://github.com/apache/druid/pull/19510#discussion_r3995012231
########## extensions-contrib/druid-iceberg-extensions/src/main/java/org/apache/druid/iceberg/input/IcebergArrowInputSourceReader.java: ########## @@ -0,0 +1,483 @@ +/* + * 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.iceberg.input; + +import com.google.common.collect.Maps; +import org.apache.arrow.vector.FieldVector; +import org.apache.druid.data.input.ColumnsFilter; +import org.apache.druid.data.input.InputRow; +import org.apache.druid.data.input.InputRowListPlusRawValues; +import org.apache.druid.data.input.InputRowSchema; +import org.apache.druid.data.input.InputSourceReader; +import org.apache.druid.data.input.InputStats; +import org.apache.druid.data.input.MapBasedInputRow; +import org.apache.druid.error.DruidException; +import org.apache.druid.iceberg.filter.IcebergFilter; +import org.apache.druid.java.util.common.parsers.CloseableIterator; +import org.apache.iceberg.CombinedScanTask; +import org.apache.iceberg.FileScanTask; +import org.apache.iceberg.Schema; +import org.apache.iceberg.Table; +import org.apache.iceberg.TableScan; +import org.apache.iceberg.arrow.vectorized.ArrowReader; +import org.apache.iceberg.arrow.vectorized.ColumnVector; +import org.apache.iceberg.arrow.vectorized.ColumnarBatch; +import org.apache.iceberg.io.CloseableIterable; +import org.apache.iceberg.types.Type; +import org.apache.iceberg.types.Types; +import org.apache.iceberg.util.TableScanUtil; +import org.joda.time.DateTime; + +import javax.annotation.Nullable; +import java.io.IOException; +import java.util.ArrayList; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.concurrent.TimeUnit; +import java.util.stream.Collectors; + +/** + * Reads an Iceberg table via iceberg-arrow's {@link ArrowReader}, yielding {@link InputRow} objects. + * + * Type coercion and compatible schema evolution are handled by the Iceberg library. Druid only consumes + * the resulting {@link ColumnarBatch} batches and maps them to {@link MapBasedInputRow}. + * + * Column projection and predicate push-down are applied at scan planning time so only requested + * columns and matching files are read from storage. + * + * Note: iceberg-arrow currently supports Parquet data files only. ORC and Avro files will throw + * {@link UnsupportedOperationException} at read time. Delete-file snapshots are rejected because + * iceberg-arrow does not apply equality or positional deletes. + */ +public class IcebergArrowInputSourceReader implements InputSourceReader +{ + static final int DEFAULT_BATCH_SIZE = 1024; + + private final Table table; + @Nullable + private final IcebergFilter icebergFilter; + @Nullable + private final DateTime snapshotTime; + private final boolean caseSensitive; + private final InputRowSchema schema; + private final int batchSize; + private final ResidualFilterMode residualFilterMode; + + public IcebergArrowInputSourceReader( + final Table table, + @Nullable final IcebergFilter icebergFilter, + @Nullable final DateTime snapshotTime, + final boolean caseSensitive, + final InputRowSchema schema, + final int batchSize + ) + { + this(table, icebergFilter, snapshotTime, caseSensitive, schema, batchSize, ResidualFilterMode.IGNORE); + } + + public IcebergArrowInputSourceReader( + final Table table, + @Nullable final IcebergFilter icebergFilter, + @Nullable final DateTime snapshotTime, + final boolean caseSensitive, + final InputRowSchema schema, + final int batchSize, + final ResidualFilterMode residualFilterMode + ) + { + this.table = table; + this.icebergFilter = icebergFilter; + this.snapshotTime = snapshotTime; + this.caseSensitive = caseSensitive; + this.schema = schema; + this.batchSize = batchSize; + this.residualFilterMode = residualFilterMode; + } + + @Override + public CloseableIterator<InputRow> read(@Nullable final InputStats inputStats) throws IOException + { + final TableScan scan = buildScan(); + validateNoDeleteFiles(scan); + validateDecimalPrecision(scan); + final CloseableIterable<CombinedScanTask> tasks = TableScanUtil.planTasks( + scan.planFiles(), + scan.targetSplitSize(), + scan.splitLookback(), + scan.splitOpenFileCost() + ); + final ClassLoader extensionClassLoader = IcebergArrowInputSourceReader.class.getClassLoader(); + final ClassLoader originalClassLoader = Thread.currentThread().getContextClassLoader(); + ArrowReader arrowReader = null; + boolean ownershipTransferred = false; + try { + Thread.currentThread().setContextClassLoader(extensionClassLoader); + arrowReader = new ArrowReader(scan, batchSize, true); + final org.apache.iceberg.io.CloseableIterator<ColumnarBatch> batchIter = arrowReader.open(tasks); + final CloseableIterator<InputRow> iterator = new ArrowInputRowIterator( + batchIter, + arrowReader, + tasks, + inputStats != null ? inputStats : new NoopInputStats(), + scan.schema(), + extensionClassLoader + ); + ownershipTransferred = true; + return iterator; + } + finally { + Thread.currentThread().setContextClassLoader(originalClassLoader); + if (!ownershipTransferred) { + try { + if (arrowReader != null) { + arrowReader.close(); + } + } + finally { + tasks.close(); + } + } + } + } + + private void validateNoDeleteFiles(final TableScan scan) throws IOException + { + try (CloseableIterable<FileScanTask> fileTasks = scan.planFiles()) { + for (FileScanTask fileTask : fileTasks) { + if (!fileTask.deletes().isEmpty()) { + throw DruidException.forPersona(DruidException.Persona.USER) + .ofCategory(DruidException.Category.UNSUPPORTED) + .build( + "Arrow reader does not support Iceberg snapshots with delete files. " + + "Use a delete-aware input path." + ); + } + } + } + } + + private void validateDecimalPrecision(final TableScan scan) + { + for (final Types.NestedField field : scan.schema().columns()) { + if (field.type().typeId() == Type.TypeID.DECIMAL + && ((Types.DecimalType) field.type()).precision() > 18) { + throw DruidException.forPersona(DruidException.Persona.USER) + .ofCategory(DruidException.Category.UNSUPPORTED) + .build( + "Arrow reader does not support decimal fields with precision greater than 18. " + + "Use the standard Iceberg reader." + ); + } + } + } + + @Override + public CloseableIterator<InputRowListPlusRawValues> sample() throws IOException + { + final CloseableIterator<InputRow> rows = read(new NoopInputStats()); + return new CloseableIterator<InputRowListPlusRawValues>() + { + @Override + public boolean hasNext() + { + return rows.hasNext(); + } + + @Override + public InputRowListPlusRawValues next() + { + final InputRow row = rows.next(); + return InputRowListPlusRawValues.of(row, ((MapBasedInputRow) row).getEvent()); + } + + @Override + public void close() throws IOException + { + rows.close(); + } + }; + } + + private TableScan buildScan() + { + TableScan scan = table.newScan().caseSensitive(caseSensitive); + + if (snapshotTime != null) { + scan = scan.asOfTime(snapshotTime.getMillis()); + } + + final List<String> projection = projectedColumns(scan.schema()); + if (projection != null) { + scan = scan.select(projection); + } + if (icebergFilter != null) { + scan = icebergFilter.filter(scan); + if (residualFilterMode == ResidualFilterMode.IGNORE) { + scan = scan.ignoreResiduals(); + } + } + return scan; + } + + /** Projection authority is ColumnsFilter, not DimensionsSpec. Mirrors DeltaInputSource#pruneSchema. */ + @Nullable + private List<String> projectedColumns(final Schema scanSchema) + { + final ColumnsFilter filter = schema.getColumnsFilter(); + final List<String> allColumns = scanSchema.columns().stream() + .map(Types.NestedField::name) + .collect(Collectors.toList()); + final List<String> filtered = allColumns.stream() + .filter(filter::apply) + .collect(Collectors.toList()); + if (filtered.equals(allColumns)) { + return null; + } + final String tsCol = schema.getTimestampSpec().getTimestampColumn(); + if (tsCol != null && allColumns.contains(tsCol) && !filtered.contains(tsCol)) { + filtered.add(tsCol); + } + return filtered; + } + + private InputRow batchRowToInputRow( + final ColumnarBatch batch, + final int rowIdx, + final Schema readSchema + ) + { + final int numCols = batch.numCols(); + final Map<String, Object> event = Maps.newHashMapWithExpectedSize(numCols); + for (int col = 0; col < numCols; col++) { + final ColumnVector column = batch.column(col); + final Types.NestedField field = readSchema.columns().get(col); + if (!column.isNullAt(rowIdx)) { + event.put(field.name(), extractValue(column, field.type(), rowIdx)); + } + } + final long timestamp = schema.getTimestampSpec().extractTimestamp(event).getMillis(); + final List<String> dimensions = resolveDimensions(readSchema); + return new MapBasedInputRow(timestamp, dimensions, event); + } + + private List<String> resolveDimensions(final Schema readSchema) + { + final List<String> configured = schema.getDimensionsSpec().getDimensionNames(); Review Comment: @Shekharrajak For this one, I think you can decide whether to fix it OR document it as this is not a core extension and exists in the opt-in path -- This is an automated message from the Apache Git Service. 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