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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-2724) Query with large number of guideposts is slower compared to no stats
Date Sun, 03 Jul 2016 14:44:11 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-2724?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15360562#comment-15360562
] 

Lars Hofhansl commented on PHOENIX-2724:
----------------------------------------

Note that this was slower, because I had churned the STATS table a lot for testing.

> Query with large number of guideposts is slower compared to no stats
> --------------------------------------------------------------------
>
>                 Key: PHOENIX-2724
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-2724
>             Project: Phoenix
>          Issue Type: Bug
>    Affects Versions: 4.7.0
>         Environment: Phoenix 4.7.0-RC4, HBase-0.98.17 on a 8 node cluster
>            Reporter: Mujtaba Chohan
>            Assignee: Lars Hofhansl
>             Fix For: 4.8.0
>
>         Attachments: 2724.txt, PHOENIX-2724.patch, PHOENIX-2724_addendum.patch, PHOENIX-2724_v2.patch
>
>
> With 1MB guidepost width for ~900GB/500M rows table. Queries with short scan range gets
significantly slower.
> Without stats:
> {code}
> select * from T limit 10; // query execution time <100 msec
> {code}
> With stats:
> {code}
> select * from T limit 10; // query execution time >20 seconds
> Explain plan: CLIENT 876085-CHUNK 476569382 ROWS 876060986727 BYTES SERIAL 1-WAY FULL
SCAN OVER T SERVER 10 ROW LIMIT CLIENT 10 ROW LIMIT
> {code}



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