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From "Tony Brusseau (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6226) enhance optmizer to use multiple probes into multiple indexes to satisfy OR queries on different columns.
Date Fri, 24 May 2013 16:28:24 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13666431#comment-13666431
] 

Tony Brusseau commented on DERBY-6226:
--------------------------------------

I think for the cases that can easily be handled as a union, one might want to consider parallelizing
the query satisfaction. I don't know, maybe you do this already for unions 8-). Also since
all of these will have the same FROM clause, any subselects in there should only be evaluated
once.
                
> enhance optmizer to use multiple probes into multiple indexes to satisfy OR queries on
different columns.
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-6226
>                 URL: https://issues.apache.org/jira/browse/DERBY-6226
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.8.3.1, 10.11.0.0
>            Reporter: Mike Matrigali
>
> For queries of the type:
> select * from a where col1 = ? or col2 = ?
> and good indexes exist on col1 and col2 it would optimal if derby could execute a plan
that
> did an index scan first on the col1 index and then an index scan on col2 index.  
> Currently it looks like derby will do a full index scan if col1 and col2 are in any index,
or a full table
> scan otherwise.

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