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From "Dustin T. Clifford" <DCliff...@isdcorporation.com>
Subject Slow performance on 5 or more joins in a star schema
Date Tue, 28 Jul 2009 21:57:37 GMT
All,

We have implemented a star schema and we are noticing that queries involving 5 or more joins
perform very slowly. We have, also, noticed that batch updates and deletes perform slowly.
We support multiple databases and, as we improve on performance in SQL Server and Oracle,
we notice a trend in the opposite direction with Derby.

I know that the Derby optimizer use to only consider  left-deep  trees. Is this still true
or is there another optimizer that we can use? Does anybody have any advise on working in
a manner that can provide good performance on Derby, SQL Server and Oracle? Any advice would
be appreciated.

Dustin Clifford


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