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Posted to derby-dev@db.apache.org by "Bhathiya Supun (JIRA)" <ji...@apache.org> on 2015/11/30 17:47:11 UTC

[jira] [Commented] (DERBY-4327) Implement optimizer support for bushy trees.

    [ 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)?
Thanks

> 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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