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https://issues.apache.org/jira/browse/HIVE-18079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16309158#comment-16309158
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Gopal V commented on HIVE-18079:
--------------------------------

With a clean run, will disable CBO rotating that join to make the tez bucket 
mapjoin test useful again.

> 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
>         Attachments: HIVE-18079.1.patch, HIVE-18079.2.patch, 
> HIVE-18079.4.patch, HIVE-18079.5.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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