Re: covariance calculation - need help optimizing query
Posted by:
Jay Pipes
Date: September 06, 2005 12:24PM
Unless you've got an index on (name,date,observationType), the query will not perform particularly well. Also, Felix makes a good point; you are precluding the use of an index on the name field by using a non-deterministic function on the left side of the equation. Change it to what Felix wrote, add an index on (name, date, observationType) and post the EXPLAIN SELECT.
Jay Pipes
Community Relations Manager, North America, MySQL Inc.
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Re: covariance calculation - need help optimizing query
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