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https://issues.apache.org/jira/browse/HIVE-4701?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eric Hanson resolved HIVE-4701.
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Resolution: Duplicate
Duplicate of HIVE-5583
> Optimize filter Column IN ( list-of-constants ) for vectorized execution
> ------------------------------------------------------------------------
>
> Key: HIVE-4701
> URL: https://issues.apache.org/jira/browse/HIVE-4701
> Project: Hive
> Issue Type: Sub-task
> Reporter: Eric Hanson
>
> OR filters have been optimized to run with vectorized query execution. IN
> filters of the form "Column IN (list-of-constants)" are a special case of OR.
> However, IN does not vectorized currently.
> E.g.
> select ddate, count\(\*\) from factsqlengineam_vec_orc where ddate =
> "2012-05-19 00:00:00" OR ddate = "2012-05-20 00:00:00" or ddate = "2012-05-21
> 00:00:00" group by ddate;
> takes about 23 seconds of CPU and
> select ddate, count\(\*\) from factsqlengineam_vec_orc where ddate IN
> ("2012-05-19 00:00:00", "2012-05-20 00:00:00", "2012-05-21 00:00:00") group
> by ddate;
> takes about 153 seconds of CPU.
> A simple fix may be that for short IN lists (say <= 64 elements) we turn them
> into OR by manipulating the query tree before planning whether vectorization
> can be used.
> A more complex fix that covers more cases would be to turn longer IN lists
> into a join so when we eventually support vectorized joins it will be fast.
> An intermediate approach might be to implement a special IN filter operator
> that stores the constant values in a sorted array or high-performance hash
> table (like Cuckoo hashing).
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