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Displaying posts with tag: mysql preformance regression (reset)
MySQL 5.1 - query optimizer regression

Since few days I was debugging a case from Yahoo! Japan team (thanks to Akira Kitada) where the query runs fine in about 0 secs with the 5.1.16 build where as the same query takes almost close to 2 minutes with the latest 5.1.22 release.

One can simply identify that this is a optimizer issue as it is not picking the right index. Lets consider the following two tables urls and urls_categories

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| urls  | CREATE TABLE `urls` (
  `url_id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `url` VARBINARY(2000) NOT NULL,
  `url_status` …
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