Our Dell PowerEdge 2950 Servers for the new DB Cluster has just arrived and I’m very excited, unpacking them.

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EXPLAIN is not the only way to analyze query perfomance im MySql because some things are not being taken into account. For example LIMIT clauses or the cost of the optimizer. There is also the mk-query-profiler.

An interesting way to compare the performance of two queries is to use mk-query-profiler along with diff

Here’s how you do it. As an example I take the queries from this mysql performance blog article article. Because I’d like to learn what excactly SQL_CALC_FOUND_ROWS does.

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