Details
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Improvement
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Status: Open
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Major
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Resolution: Unresolved
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None
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None
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Normal
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Performance, Seen in production
Description
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
Attachments
Issue Links
- is related to
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DERBY-1907 Improve optimizer to prune query plans more aggressively.
- Open