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https://issues.apache.org/jira/browse/HIVE-17626?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16383233#comment-16383233
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Zoltan Haindrich commented on HIVE-17626:
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failures are not related
> Query reoptimization using cached runtime statistics
> ----------------------------------------------------
>
> Key: HIVE-17626
> URL: https://issues.apache.org/jira/browse/HIVE-17626
> Project: Hive
> Issue Type: New Feature
> Components: Logical Optimizer
> Affects Versions: 3.0.0
> Reporter: Prasanth Jayachandran
> Assignee: Zoltan Haindrich
> Priority: Major
> Attachments: HIVE-17626.01.patch, HIVE-17626.01wip01.patch,
> HIVE-17626.02.patch, HIVE-17626.03.patch, HIVE-17626.04.patch,
> HIVE-17626.05.patch, HIVE-17626.06.patch, runtimestats.patch
>
>
> Something similar to "EXPLAIN ANALYZE" where we annotate explain plan with
> actual and estimated statistics. The runtime stats can be cached at query
> level and subsequent execution of the same query can make use of the cached
> statistics from the previous run for better optimization.
> Some use cases,
> 1) re-planning join query (mapjoin failures can be converted to shuffle joins)
> 2) better statistics for table scan operator if dynamic partition pruning is
> involved
> 3) Better estimates for bloom filter initialization (setting expected entries
> during merge)
> This can extended to support wider queries by caching fragments of operator
> plans scanning same table(s) or matching some operator sequences.
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