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From "jiraposter@reviews.apache.org (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-2035) Use block-level merge for RCFile if merging intermediate results are needed
Date Tue, 21 Jun 2011 23:34:49 GMT

    [ https://issues.apache.org/jira/browse/HIVE-2035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13052940#comment-13052940
] 

jiraposter@reviews.apache.org commented on HIVE-2035:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/935/#review875
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Can you make sure that in the test cases, the query need the merge step?

- Siying


On 2011-06-20 19:20:53, Franklin Hu wrote:
bq.  
bq.  -----------------------------------------------------------
bq.  This is an automatically generated e-mail. To reply, visit:
bq.  https://reviews.apache.org/r/935/
bq.  -----------------------------------------------------------
bq.  
bq.  (Updated 2011-06-20 19:20:53)
bq.  
bq.  
bq.  Review request for hive.
bq.  
bq.  
bq.  Summary
bq.  -------
bq.  
bq.  For a table stored as RCFile, intermediate results are sometimes merged if those files
are below a certain threshold. For RCFiles, we can do a block level merge that does not deserialize
the blocks and is more efficient. This patch leverages the existing code used to merge for
ALTER TABLE ... CONCATENATE.
bq.  
bq.  
bq.  This addresses bug HIVE-2035.
bq.      https://issues.apache.org/jira/browse/HIVE-2035
bq.  
bq.  
bq.  Diffs
bq.  -----
bq.  
bq.    trunk/common/src/java/org/apache/hadoop/hive/conf/HiveConf.java 1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/TaskFactory.java 1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/io/rcfile/merge/BlockMergeTask.java 1136090

bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/io/rcfile/merge/MergeWork.java 1136090

bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/io/rcfile/merge/RCFileBlockMergeRecordReader.java
1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/io/rcfile/merge/RCFileKeyBufferWrapper.java
1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/io/rcfile/merge/RCFileMergeMapper.java
1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/optimizer/GenMRFileSink1.java 1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/plan/ConditionalResolverMergeFiles.java
1136090 
bq.    trunk/ql/src/java/org/apache/hadoop/hive/ql/plan/MapredWork.java 1136090 
bq.    trunk/ql/src/test/queries/clientpositive/rcfile_createas1.q PRE-CREATION 
bq.    trunk/ql/src/test/queries/clientpositive/rcfile_merge1.q PRE-CREATION 
bq.    trunk/ql/src/test/queries/clientpositive/rcfile_merge2.q PRE-CREATION 
bq.    trunk/ql/src/test/queries/clientpositive/rcfile_merge3.q PRE-CREATION 
bq.    trunk/ql/src/test/queries/clientpositive/rcfile_merge4.q PRE-CREATION 
bq.    trunk/ql/src/test/results/clientpositive/rcfile_createas1.q.out PRE-CREATION 
bq.    trunk/ql/src/test/results/clientpositive/rcfile_merge1.q.out PRE-CREATION 
bq.    trunk/ql/src/test/results/clientpositive/rcfile_merge2.q.out PRE-CREATION 
bq.    trunk/ql/src/test/results/clientpositive/rcfile_merge3.q.out PRE-CREATION 
bq.    trunk/ql/src/test/results/clientpositive/rcfile_merge4.q.out PRE-CREATION 
bq.  
bq.  Diff: https://reviews.apache.org/r/935/diff
bq.  
bq.  
bq.  Testing
bq.  -------
bq.  
bq.  
bq.  Thanks,
bq.  
bq.  Franklin
bq.  
bq.



> Use block-level merge for RCFile if merging intermediate results are needed
> ---------------------------------------------------------------------------
>
>                 Key: HIVE-2035
>                 URL: https://issues.apache.org/jira/browse/HIVE-2035
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Ning Zhang
>            Assignee: Franklin Hu
>         Attachments: hive-2035.1.patch
>
>
> Currently if hive.merge.mapredfiles and/or hive.merge.mapfile is set to true the intermediate
data could be merged using an additional MapReduce job. This could be quite expensive if the
data size is large. With HIVE-1950, merging can be done in the RCFile block level so that
it bypasses the (de-)compression, (de-)serialization phases. This could improve the merge
process significantly. 
> This JIRA should handle the case where the input table is not stored in RCFile, but the
destination table is (which requires the intermediate data should be stored in the same format
as the destination table). 

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