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From "Bhathiya Supun (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-4327) Implement optimizer support for bushy trees.
Date Mon, 30 Nov 2015 16:47:11 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4327?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15032061#comment-15032061

Bhathiya Supun commented on DERBY-4327:

We are interested in working on this issue as part of Database Internals module at the university.
3 of us will be working on this for 6 to 8 weeks. Will this be suitable considered the time
limitations (and the fact that we are new to Derby project)?

> Implement optimizer support for bushy trees.
> --------------------------------------------
>                 Key: DERBY-4327
>                 URL: https://issues.apache.org/jira/browse/DERBY-4327
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Rick Hillegas
>              Labels: derby_triage10_10
> Currently, the optimizer only considers left-deep trees. For queries involving many tables,
the best plan may be bushy. In this email thread, a user notes poor performance by Derby on
queries involving 5 or more tables: http://www.nabble.com/Slow-performance-on-5-or-more-joins-in-a-star-schema-tt24708686.html

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