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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-18079) Statistics: Allow HyperLogLog to be merged to the lowest-common-denominator bit-size
Date Wed, 16 May 2018 07:26:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-18079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16476962#comment-16476962
] 

Prasanth Jayachandran commented on HIVE-18079:
----------------------------------------------

tez_vector_dynpart_hashjoin_1.q diff is handled in HIVE-19555. Removed from this patch. 

> Statistics: Allow HyperLogLog to be merged to the lowest-common-denominator bit-size
> ------------------------------------------------------------------------------------
>
>                 Key: HIVE-18079
>                 URL: https://issues.apache.org/jira/browse/HIVE-18079
>             Project: Hive
>          Issue Type: Improvement
>          Components: Standalone Metastore, Statistics
>    Affects Versions: 3.0.0
>            Reporter: Gopal V
>            Assignee: Gopal V
>            Priority: Major
>         Attachments: HIVE-18079.1.patch, HIVE-18079.10.patch, HIVE-18079.11.patch, HIVE-18079.12.patch,
HIVE-18079.13.patch, HIVE-18079.14.patch, HIVE-18079.2.patch, HIVE-18079.4.patch, HIVE-18079.5.patch,
HIVE-18079.6.patch, HIVE-18079.7.patch, HIVE-18079.8.patch, HIVE-18079.9.patch
>
>
> HyperLogLog can merge a 14 bit HLL into a 10 bit HLL bitset, because of its mathematical
hash distribution & construction.
> Allow the squashing of a 14 bit HLL -> 10 bit HLL without needing a second scan over
the data-set.



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