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https://issues.apache.org/jira/browse/PARQUET-1381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17092880#comment-17092880
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ASF GitHub Bot commented on PARQUET-1381:
-----------------------------------------
shangxinli commented on a change in pull request #775:
URL: https://github.com/apache/parquet-mr/pull/775#discussion_r415418003
##########
File path:
parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileWriter.java
##########
@@ -919,6 +895,59 @@ public void appendRowGroup(SeekableInputStream from,
BlockMetaData rowGroup,
endBlock();
}
+ /**
+ * Merges adjacent row groups in the supplied files while maintaining that
the new groups is no more than the specified
+ * maxRowGroupSize
+ * @param inputFiles input files to merge
+ * @param maxRowGroupSize the maximum size in bytes the new created groups
can be
+ * @param useV2Writer whether to use a V2 encoding based writer when
rewriting dictionary encoded pages
+ * @param compression compression to use when writing
+ * @throws IOException
+ */
+ public void mergeRowGroups(List<InputFile> inputFiles, long maxRowGroupSize,
boolean useV2Writer, CompressionCodecName compression) throws IOException {
Review comment:
I prefer not to unless you strongly think we should.
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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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