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From "Mike Matrigali (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 Thu, 23 May 2013 22:39:20 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13665790#comment-13665790
] 

Mike Matrigali commented on DERBY-6226:
---------------------------------------

It may be worth seeing if rewriting the query as a union allows derby to use the 2 different
indexes.  And if so could derby internally do that kind of query translation?
                
> 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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