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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-4686) Phoenix stats does not account for server side limit push downs
Date Wed, 25 Apr 2018 23:34:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16453236#comment-16453236
] 

James Taylor commented on PHOENIX-4686:
---------------------------------------

Thanks for the additional tests, [~abhishek.chouhan]. I've attached a new version of the patch
that:
- includes test for query with WHERE clause that doesn't get compiled out
- takes into account parallelized queries with LIMIT clause

One clarification, [~cody.marcel@gmail.com] - by "query with no where clause", we really mean
"query with where clause that does get compiled out". If the WHERE IN clause is a point lookup,
then that gets compiled into a scan without a filter. On the other hand, if you have a WHERE
clause that filters on a non PK column, that'll end up as a filter (in which case we can't
estimate the rows/bytes scanned based on the LIMIT clause).

> Phoenix stats does not account for server side limit push downs
> ---------------------------------------------------------------
>
>                 Key: PHOENIX-4686
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4686
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Abhishek Singh Chouhan
>            Assignee: Abhishek Singh Chouhan
>            Priority: Major
>             Fix For: 4.14.0, 5.0.0
>
>         Attachments: PHOENIX-4686-wip.master.patch, PHOENIX-4686.master.patch, PHOENIX-4686_v2.patch,
PHOENIX-4686_wip1.patch
>
>
> For a query like SELECT * FROM FOO LIMIT 10 the EST_BYTES_READ does not take into account
a limit correctly when there's no WHERE clause (or a WHERE clause that gets compiled out into
start/stop row key on the scan).



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