Tag: MySQL Query Performance

Performance

MySQL Query Performance: Not Just Indexes

  In this blog post, I’ll look at whether optimizing indexing is always the key to improving MySQL query performance (spoiler, it isn’t). As we look at MySQL query performance, our first concern is often whether a query is using the right indexes to retrieve the data. This is based on the assumption that finding the data …

Performance, Troubleshooting

Improved Query Performance by Using Derived Table instead of IN-subquery

MySQL 5.6 introduced semi-join transformation for IN-subqueries. This opened up for several new ways to execute such subqueries; one was no longer tied to executing the subquery once for every row of the outer query. This dramatically improved the performance of many such queries. However, semi-join transformation does not apply to all types of queries. …