MaxNevermind commented on code in PR #1273:
URL: https://github.com/apache/parquet-mr/pull/1273#discussion_r1536910444
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parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/ParquetRewriter.java:
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@@ -904,4 +953,171 @@ public byte[] getDictPageAAD() {
return this.dictPageAAD;
}
}
+
+ private static class RightColumnWriter {
+ private final Queue<TransParquetFileReader> inputFiles;
+ private final ParquetRewriter parquetRewriter;
+ private final ParquetFileWriter writer;
+ private final MessageType schema;
+ private final Map<ColumnPath, ColumnDescriptor> descriptorsMap;
+ private final Map<ColumnDescriptor, ColumnReader> colReaders = new
HashMap<>();
+ private final Map<ColumnDescriptor, ColumnChunkPageWriteStore> cPageStores
= new HashMap<>();
+ private final Map<ColumnDescriptor, ColumnWriteStore> cStores = new
HashMap<>();
+ private final Map<ColumnDescriptor, ColumnWriter> cWriters = new
HashMap<>();
+ private int rowGroupIdxIn = 0;
+ private int rowGroupIdxOut = 0;
+ private int writtenFromBlock = 0;
+
+ public RightColumnWriter(Queue<TransParquetFileReader> inputFiles,
ParquetRewriter parquetRewriter)
+ throws IOException {
+ this.inputFiles = inputFiles;
+ this.parquetRewriter = parquetRewriter;
+ this.writer = parquetRewriter.writer;
+ this.schema =
inputFiles.peek().getFooter().getFileMetaData().getSchema();
+ this.descriptorsMap = this.schema.getColumns().stream()
+ .collect(Collectors.toMap(x -> ColumnPath.get(x.getPath()), x -> x));
+ initReaders();
+ initWriters();
+ }
+
+ public void writeRows(int rowGroupIdx, long rowsToWrite) throws
IOException {
+ if (rowGroupIdxIn != rowGroupIdx) {
+ rowGroupIdxIn = rowGroupIdx;
+ flushWriters();
+ initWriters();
+ }
+ while (rowsToWrite > 0) {
+ List<BlockMetaData> blocks = inputFiles.peek().getFooter().getBlocks();
+ BlockMetaData block = blocks.get(rowGroupIdxOut);
+ List<ColumnChunkMetaData> chunks = block.getColumns();
+ long leftInBlock = block.getRowCount() - writtenFromBlock;
+ long writeFromBlock = Math.min(rowsToWrite, leftInBlock);
+ for (ColumnChunkMetaData chunk : chunks) {
+ if (chunk.isEncrypted()) {
+ throw new IOException("Column " + chunk.getPath().toDotString() +
" is encrypted");
+ }
+ ColumnDescriptor descriptor = descriptorsMap.get(chunk.getPath());
+ copyValues(descriptor, writeFromBlock);
+ }
+ rowsToWrite -= writeFromBlock;
+ writtenFromBlock += writeFromBlock;
+ if (rowsToWrite > 0 || (block.getRowCount() == writtenFromBlock)) {
+ rowGroupIdxOut++;
+ if (rowGroupIdxOut == blocks.size()) {
+ inputFiles.poll();
+ rowGroupIdxOut = 0;
+ }
+ writtenFromBlock = 0;
+ // this is called after all rows are processed
+ initReaders();
+ }
+ }
+ flushWriters();
+ }
+
+ private void flushWriters() throws IOException {
+ cStores.values().forEach(cStore -> {
+ cStore.flush();
+ cStore.close();
+ });
+ cWriters.values().forEach(ColumnWriter::close);
+ for (ColumnDescriptor descriptor : descriptorsMap.values()) {
+ if (cPageStores.containsKey(descriptor))
+ cPageStores.get(descriptor).flushToFileWriter(writer);
+ }
+ cStores.clear();
+ cWriters.clear();
+ cPageStores.clear();
+ }
+
+ private void initWriters() {
+ if (!inputFiles.isEmpty()) {
+ List<BlockMetaData> blocks = inputFiles.peek().getFooter().getBlocks();
+ descriptorsMap.forEach((columnPath, descriptor) -> {
+ ColumnChunkMetaData chunk =
blocks.get(rowGroupIdxOut).getColumns().stream()
+ .filter(x -> x.getPath() == columnPath)
+ .findFirst()
+ .orElseThrow(() -> new IllegalStateException(
+ "Could not find column [" + columnPath.toDotString() +
"]."));
+ int bloomFilterLength = chunk.getBloomFilterLength();
+ ParquetProperties.WriterVersion writerVersion =
+ chunk.getEncodingStats().usesV2Pages()
+ ? ParquetProperties.WriterVersion.PARQUET_2_0
+ : ParquetProperties.WriterVersion.PARQUET_1_0;
+ ParquetProperties props = ParquetProperties.builder()
+ .withWriterVersion(writerVersion)
+ .withBloomFilterEnabled(bloomFilterLength > 0)
+ .build();
+ CodecFactory codecFactory = new CodecFactory(new Configuration(),
props.getPageSizeThreshold());
+ CompressionCodecFactory.BytesInputCompressor compressor =
+ codecFactory.getCompressor(chunk.getCodec());
Review Comment:
Originally I planned to skip the support for pruning/masking/codec
changing/encryption for the right side, you can find the checks for that in
[RewriteOptions
builder](https://github.com/MaxNevermind/parquet-mr/blob/883e93586589f2027e9187d2b4eeda8c4e8e2b89/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/rewrite/RewriteOptions.java#L409).
My reasoning was that parquet joiner is for a niche use-case, primarily for
large dataset stitching to save resource. Let me know if you want me to make
those not-supported extra features. The answer applies for other questions
bellow related to missing features on the right.
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