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https://issues.apache.org/jira/browse/PARQUET-1381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17088099#comment-17088099
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ASF GitHub Bot commented on PARQUET-1381:
-----------------------------------------
brimzi commented on a change in pull request #775:
URL: https://github.com/apache/parquet-mr/pull/775#discussion_r411708296
##########
File path:
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/RowGroupMerger.java
##########
@@ -0,0 +1,634 @@
+/*
+ * 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.parquet.hadoop;
+
+import static java.lang.String.format;
+import static org.apache.parquet.column.ValuesType.DEFINITION_LEVEL;
+import static org.apache.parquet.column.ValuesType.REPETITION_LEVEL;
+import static org.apache.parquet.column.ValuesType.VALUES;
+import static org.apache.parquet.hadoop.ParquetFileWriter.getColumnsInOrder;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.parquet.Preconditions;
+import org.apache.parquet.bytes.ByteBufferInputStream;
+import org.apache.parquet.bytes.BytesInput;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.Dictionary;
+import org.apache.parquet.column.Encoding;
+import org.apache.parquet.column.ParquetProperties;
+import org.apache.parquet.column.page.DataPage;
+import org.apache.parquet.column.page.DataPageV1;
+import org.apache.parquet.column.page.DataPageV2;
+import org.apache.parquet.column.page.DictionaryPage;
+import org.apache.parquet.column.page.PageReadStore;
+import org.apache.parquet.column.page.PageReader;
+import org.apache.parquet.column.values.ValuesReader;
+import org.apache.parquet.column.values.ValuesWriter;
+import org.apache.parquet.compression.CompressionCodecFactory;
+import org.apache.parquet.hadoop.metadata.BlockMetaData;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+import org.apache.parquet.hadoop.metadata.CompressionCodecName;
+import org.apache.parquet.io.InputFile;
+import org.apache.parquet.io.ParquetDecodingException;
+import org.apache.parquet.schema.MessageType;
+import org.apache.parquet.schema.PrimitiveType;
+
+class RowGroupMerger {
+
+ private final MessageType schema;
+ private final CodecFactory.BytesInputCompressor compressor;
+ private final ParquetProperties parquetProperties;
+
+ RowGroupMerger(MessageType schema, CompressionCodecName compression, boolean
useV2ValueWriter) {
+ this(schema, new Configuration(), compression, useV2ValueWriter);
+ }
+
+ RowGroupMerger(MessageType schema, Configuration conf, CompressionCodecName
compression, boolean useV2ValueWriter) {
+ this(schema, conf, compression, createParquetProperties(useV2ValueWriter));
+ }
+
+ RowGroupMerger(MessageType schema, Configuration conf, CompressionCodecName
compression, ParquetProperties parquetProperties) {
+ this.schema = schema;
+ this.parquetProperties = parquetProperties;
+ this.compressor = new CodecFactory(conf,
this.parquetProperties.getPageSizeThreshold()).getCompressor(compression);
+ }
+
+ /**
+ * Merges the row groups making sure that new row groups do not exceed the
supplied maxRowGroupSize
+ *
+ * @param inputFiles input files to merge
+ * @param maxRowGroupSize the max limit for new blocks
+ * @param writer writer to write the new blocks to
+ * @throws IOException if an IO error occurs
+ */
+ void merge(List<InputFile> inputFiles, final long maxRowGroupSize,
ParquetFileWriter writer) throws IOException {
+
+ SizeEstimator estimator = new SizeEstimator(compressor.getCodecName() !=
CompressionCodecName.UNCOMPRESSED);
+ MutableMergedBlock mergedBlock = null;
+ for (InputFile file : inputFiles) {
+ try (ParquetFileReader reader = ParquetFileReader.open(file)) {
+
+ for (BlockMetaData blockMeta : reader.getRowGroups()) {
+ PageReadStore group = reader.readNextRowGroup();
+ Preconditions.checkState(group != null,
+ "number of groups returned by FileReader does not match metadata");
+
+ if (mergedBlock != null && mergedBlock.getCompressedBytesSize() +
estimator.estimate(blockMeta) > maxRowGroupSize) {
+ saveBlockTo(mergedBlock, writer);
+ mergedBlock = null;
+ }
+
+ if (mergedBlock == null && estimator.estimate(blockMeta) >
maxRowGroupSize) {
+ //save it directly without re encoding it
+ saveBlockTo(ReadOnlyMergedBlock.of(blockMeta, group, schema,
compressor), writer);
+ continue;
+ }
+
+ if (mergedBlock == null) {
+ mergedBlock = new MutableMergedBlock(schema);
+ }
+
+ long sizeBeforeMerge = mergedBlock.getCompressedBytesSize();
+ mergedBlock.merge(blockMeta, group);
+ //update our estimator
+ long currentBlockEffect = mergedBlock.getCompressedBytesSize() -
sizeBeforeMerge;
+ estimator.update(currentBlockEffect, blockMeta);
+ }
+ }
+ }
+ if (mergedBlock != null)
+ saveBlockTo(mergedBlock, writer);
+ }
+
+
+ private static void saveBlockTo(MergedBlock block, ParquetFileWriter writer)
{
+ try {
+ writer.startBlock(block.rowCount());
+
+ for (MergedColumn col : block.columnsInOrder()) {
+ writer.startColumn(col.getColumnDesc(), col.getValueCount(),
col.getCompression());
+
+ col.writeDictionaryPageTo(writer);
+ col.writeDataPagesTo(writer);
+
+ writer.endColumn();
+ }
+
+ writer.endBlock();
+ } catch (IOException e) {
+ throw new UncheckedIOException(e);
+ }
+ }
+
+ private static ParquetProperties createParquetProperties(boolean
useV2Writer) {
+ ParquetProperties.Builder builder = ParquetProperties.builder();
+ if (useV2Writer) {
+ builder.withWriterVersion(ParquetProperties.WriterVersion.PARQUET_2_0);
+ }
+ return builder.build();
+ }
+
+ private BytesInput compress(BytesInput bytes) {
+ return compress(bytes, compressor);
+ }
+
+ private static BytesInput compress(BytesInput bytes,
CompressionCodecFactory.BytesInputCompressor compressor) {
+ try {
+ return BytesInput.copy(compressor.compress(bytes));//we copy as some
compressors use shared memory
+ } catch (IOException e) {
+ throw new UncheckedIOException(e);
+ }
+ }
+
+ private static BiConsumer<ValuesReader, ValuesWriter>
createWritingBridge(PrimitiveType.PrimitiveTypeName typeName) {
+ switch (typeName) {
+ case FIXED_LEN_BYTE_ARRAY:
+ case INT96:
+ case BINARY:
+ return (src, dest) -> dest.writeBytes(src.readBytes());
+ case BOOLEAN:
+ return (src, dest) -> dest.writeBoolean(src.readBoolean());
+ case DOUBLE:
+ return (src, dest) -> dest.writeDouble(src.readDouble());
+ case FLOAT:
+ return (src, dest) -> dest.writeFloat(src.readFloat());
+ case INT32:
+ return (src, dest) -> dest.writeInteger(src.readInteger());
+ case INT64:
+ return (src, dest) -> dest.writeLong(src.readLong());
+ default:
+ throw new RuntimeException("Unsupported column primitive type: " +
typeName.name());
+ }
+ }
+
+ private static void writePageTo(DataPage dataPage, ParquetFileWriter writer)
{
+ dataPage.accept(new DataPage.Visitor<Void>() {
+ @Override
+ public Void visit(DataPageV1 page) {
+ try {
+ if (page.getIndexRowCount().isPresent()) {
+ writer.writeDataPage(page.getValueCount(),
page.getUncompressedSize(),
+ page.getBytes(), page.getStatistics(),
page.getIndexRowCount().get(), page.getRlEncoding(),
+ page.getDlEncoding(), page.getValueEncoding());
+
+ } else {
+ writer.writeDataPage(page.getValueCount(),
page.getUncompressedSize(),
+ page.getBytes(), page.getStatistics(), page.getRlEncoding(),
+ page.getDlEncoding(), page.getValueEncoding());
+ }
+ } catch (IOException e) {
+ throw new UncheckedIOException(e);
Review comment:
I am forced to wrap it here because in the Visitor interface this method
does not throw any exception, hence I am supposed to swallow all checked
exceptions in this implementation
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> Add merge blocks command to parquet-tools
> -----------------------------------------
>
> Key: PARQUET-1381
> URL: https://issues.apache.org/jira/browse/PARQUET-1381
> Project: Parquet
> Issue Type: New Feature
> Components: parquet-mr
> Affects Versions: 1.10.0
> Reporter: Ekaterina Galieva
> Assignee: Ekaterina Galieva
> Priority: Major
> Labels: pull-request-available
>
> Current implementation of merge command in parquet-tools doesn't merge row
> groups, just places one after the other. Add API and command option to be
> able to merge small blocks into larger ones up to specified size limit.
> h6. Implementation details:
> Blocks are not reordered not to break possible initial predicate pushdown
> optimizations.
> Blocks are not divided to fit upper bound perfectly.
> This is an intentional performance optimization.
> This gives an opportunity to form new blocks by coping full content of
> smaller blocks by column, not by row.
> h6. Examples:
> # Input files with blocks sizes:
> {code:java}
> [128 | 35], [128 | 40], [120]{code}
> Expected output file blocks sizes:
> {{merge }}
> {code:java}
> [128 | 35 | 128 | 40 | 120]
> {code}
> {{merge -b}}
> {code:java}
> [128 | 35 | 128 | 40 | 120]
> {code}
> {{merge -b -l 256 }}
> {code:java}
> [163 | 168 | 120]
> {code}
> # Input files with blocks sizes:
> {code:java}
> [128 | 35], [40], [120], [6] {code}
> Expected output file blocks sizes:
> {{merge}}
> {code:java}
> [128 | 35 | 40 | 120 | 6]
> {code}
> {{merge -b}}
> {code:java}
> [128 | 75 | 126]
> {code}
> {{merge -b -l 256}}
> {code:java}
> [203 | 126]{code}
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