Re: QUERY OPTIMIZATION FOR UNION ALL IN MYSQL 4.1.22
Posted by:
Rick James
Date: September 26, 2008 11:20PM
Normally it will use the FULLTEXT index first. First find all the rows that 'MATCH', then filter on the rest of the WHERE. After doing that in each SELECT, collect the rows, sort them, and finally deliver the first 5.
However, it seems that the 3rd SELECT started with the 'approved' index. Maybe a "USE INDEX (...)" on that SELECT would encourage it to use the FT index first (assuming that would help).
Sorry, just some observations, not a real answer.
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September 03, 2008 03:30AM
Re: QUERY OPTIMIZATION FOR UNION ALL IN MYSQL 4.1.22
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September 26, 2008 11:20PM
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