Lea Verou • 3/25/2010

MySQL: Are you actually utilizing your indexes?

This technical article demonstrates how subtle differences in MySQL query syntax can dramatically impact performance. By changing a WHERE clause from 'UNIX_TIMESTAMP(NOW()) - post.dateline < 86400' to 'post.dateline > UNIX_TIMESTAMP(NOW()) - 86400', query time dropped from ~10 seconds to 0.03 seconds. The author explains how the second query allows MySQL to properly utilize the B+ tree index on the dateline column, with execution plan analysis using EXPLAIN to show the performance difference.

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#indexing #mysql #Query Optimization