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Wildcard usage in mysql

Posted on 2007-08-09
Medium Priority
Last Modified: 2013-11-05
I'm finding some really strange results when I do searches on my mysql database (360k records).
For instance, if I search for JOHN%% limit 0,100 -> it returns quickly.
But if I search for JOHN%Y -> It takes forever.

Can someone tell me why some of my searches are dog slow, while others are quick?  I'm generating indexes for each column I am searching against, hoping that will help.

Running on: 4.1.22-log on Mac OSX Tiger Server
Question by:ecuguru
LVL 48

Assisted Solution

hernst42 earned 800 total points
ID: 19661038
Its because if you use JOHN%Y a whole table scan is performed, as no index can be used (string must start wirh JOHN and END with Y). If you search FOR JOHN% a index can be used, as you are only looking for a string starting with JOHN.
LVL 17

Accepted Solution

Aleksandar Bradarić earned 1200 total points
ID: 19661189
You could try using the way below to keep using the indexes and execute the query you want :)
... yourColumn LIKE 'JOHN%'  AND yourColumn LIKE '%Y' ...

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