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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-4288) Indexes not used when ordering by primary key
Date Fri, 20 Oct 2017 20:41:01 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16213200#comment-16213200
] 

James Taylor commented on PHOENIX-4288:
---------------------------------------

[~maryannxue] - this would be a good one for you if you have some spare cycles. Currently
Phoenix always chooses to optimize out an ORDER BY as opposed to optimizing based on the filter.
Since we can get at compile time the number of bytes that will be scanned if we were to optimize
based on the filter (since in this case it'd be using an index that leads with the column
being filtered on), we could make a cost based decision instead.

WDYT?

> Indexes not used when ordering by primary key
> ---------------------------------------------
>
>                 Key: PHOENIX-4288
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4288
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Marcin Januszkiewicz
>
> We have a table
> CREATE TABLE t (
>   rowkey VARCHAR PRIMARY KEY,
>   c1 VARCHAR,
>   c2 VARCHAR
> )
> which we want to query by doing partial matches on c1, and keep the ordering of the source
table:
> SELECT rowkey, c1, c2 FROM t where c1 LIKE 'X0%' ORDER BY rowkey;
> We expect most queries to select a small subset of the table, so we create an index to
speed up searches:
> CREATE LOCAL INDEX t_c1_ix ON t (c1);
> However, this index will not be used since Phoenix will always choose not to resort the
data.
> In our actual use case, adding index hints is not a practical solution.
> See also discussion at:
> https://lists.apache.org/thread.html/26ab58288eb811d2f074c3f89067163d341e5531fb581f3b2486cf43@%3Cuser.phoenix.apache.org%3E



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