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https://issues.apache.org/jira/browse/PARQUET-1381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17087267#comment-17087267
]
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_r411026823
##########
File path:
parquet-tools/src/main/java/org/apache/parquet/tools/command/MergeCommand.java
##########
@@ -18,27 +18,37 @@
*/
package org.apache.parquet.tools.command;
+import static org.apache.parquet.hadoop.ParquetWriter.DEFAULT_BLOCK_SIZE;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.UncheckedIOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.Option;
+import org.apache.commons.cli.Options;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
-import org.apache.parquet.hadoop.util.HadoopInputFile;
-import org.apache.parquet.hadoop.util.HiddenFileFilter;
+import org.apache.parquet.column.EncodingStats;
import org.apache.parquet.hadoop.ParquetFileWriter;
+import org.apache.parquet.hadoop.metadata.CompressionCodecName;
import org.apache.parquet.hadoop.metadata.FileMetaData;
+import org.apache.parquet.hadoop.metadata.ParquetMetadata;
+import org.apache.parquet.hadoop.util.HadoopInputFile;
+import org.apache.parquet.hadoop.util.HiddenFileFilter;
+import org.apache.parquet.io.InputFile;
import org.apache.parquet.tools.Main;
-import java.io.IOException;
-import java.io.PrintWriter;
-import java.util.ArrayList;
-import java.util.List;
-
public class MergeCommand extends ArgsOnlyCommand {
Review comment:
Add tests for it
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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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