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Zoltan Haindrich commented on HIVE-17626: ----------------------------------------- patch#1) contains HIVE-18805 > 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, > 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. -- This message was sent by Atlassian JIRA (v7.6.3#76005)