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Help needed on tuning query with join
Posted by: N.Z. Bear
Date: October 12, 2004 02:42PM

I'm having performance problems on a query which I believe is a result of my poor understanding of how to do an efficient join.

I have two tables: 'links', with several million rows, and 'weblogs', with ~ 15,000 rows.

I need to select a certain set of links from 'links', and look up data from 'weblogs' based on the source id found in 'links'.

So the query I structured looks like:

'select a.id,a.lookup_data,b.source_id,b.criteria from weblogs as a, left join links as b on a.id=b.source_id where b.criteria=criteria



This should only return a few hundred rows of data from links and then look up the lookup_data from weblogs. But the performance on this seems to be pretty terrible. Can anyone suggest a more efficient structure? It seems like this should be easily optimized, but my 'join' knowledge is not up to the task.

Help would be appreciated; thanks!

-N.Z. Bear
The Turth Laid Bear
http://www.truthlaidbear.com

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