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From "Eugene Koifman (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-14199) Enable Bucket Pruning for ACID tables
Date Wed, 10 Aug 2016 20:57:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-14199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15415995#comment-15415995
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Eugene Koifman commented on HIVE-14199:
---------------------------------------

I think what [~gopalv] meant by legacy is "transactional_properties=legacy"  though the issues
with streaming/bucketing were fixed long ago in HIVE-11983

> Enable Bucket Pruning for ACID tables
> -------------------------------------
>
>                 Key: HIVE-14199
>                 URL: https://issues.apache.org/jira/browse/HIVE-14199
>             Project: Hive
>          Issue Type: Improvement
>          Components: Transactions
>            Reporter: Saket Saurabh
>            Assignee: Saket Saurabh
>         Attachments: HIVE-14199.01.patch, HIVE-14199.02.patch
>
>
> Currently, ACID tables do not benefit from the bucket pruning feature introduced in HIVE-11525.
The reason for this has been the fact that bucket pruning happens at split generation level
and for ACID, traditionally the delta files were never split. The parallelism for ACID was
then restricted to the number of buckets. There would be as many splits as the number of buckets
and each worker processing one split would inevitably read all the delta files for that bucket,
even when the query may have originally required only one of the buckets to be read.
> However, HIVE-14035 now enables even the delta files to be also split. What this means
is that now we have enough information at the split generation level to determine appropriate
buckets to process for the delta files. This can efficiently allow us to prune unnecessary
buckets for delta files and will lead to good performance gain for a large number of selective
queries on ACID tables.



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