When EXPLAIN estimates can go wrong!

This is the title of my first blog post on MySQL Performance Blog. It deals with a customer case where the customer was facing a peculiar problem where the rows column in the EXPLAIN output of the query was totally off. The actual number of rows was 18 times more than the number of rows reported by MySQL in the output of EXPLAIN. Now this can be a real pain as MySQL uses “the number of rows” estimation to pick

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A step by step guide to upgrading to MySQL 5.5

MySQL 5.5 has created a lot of hype and its not just hype, there are major performance enhancements not only in the MySQL server itself but in the newer InnoDB plugin shipped with MySQL 5.5. That's exactly the reason why I have myself upgraded to MySQL 5.5 (The server running this blog run MySQL 5.5). Now since I haven't come across a guide to help in upgrading to MySQL 5.5, I thought why not make one myself