Tag: group by


Four Ways MySQL Executes GROUP BY

In this blog post, I’ll look into four ways MySQL executes GROUP BY.  In my previous blog post, we learned that indexes or other means of finding data might not be the most expensive part of query execution. For example, MySQL GROUP BY could potentially be responsible for 90% or more of the query execution time.  …


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 …