30th Mar 2008

MySQL tip: why are my joins so slow?

Never! Never join tables on fields with different types. Say, you have one table with `zip` varchar(5) and another with `zip` int(5). As a result of …left join … on a.zip=b.zip you will get perfomance loss up to 1000 times.

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This entry was posted on Sunday, March 30th, 2008 at 9:14 pm and is filed under MySQL. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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