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Message Posted: Mon, 19 Jan 2004 @ 13:52:30 GMT

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Subj:   Re: Query Optimization with Inner Joins
From:   Geoffrey Rommel

  Can someone help me out in optimizing a select query which inner joins two table one big and another small?  

  Table y has primary index on a,b,e,f,g,h ...  

  I am joining on a and b column.  

Your EXPLAIN text shows "no confidence" and "low confidence", which means you need statistics. Change the primary index on table y (the little one) to (a,b). It may be a little skewed, but don't worry about that. Collect statistics on ALL columns and indexes in that table; collect them on all indexes and join columns in the larger one. Then test again. This should make a difference.

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