Join us for our latest webinar on Thursday, April 7, at 10 am PDT (UTC-7) on Introduction to Troubleshooting Performance: What Affects Query Execution?

MySQL installations experience a multitude of issues: server hangs, wrong data stored in the database, slow running queries, stopped replications, poor user connections and many others. It’s often difficult not only to troubleshoot these issues, but to even know which tools to use.

Slow running queries, threads stacking for ages during peak times, application performance suddenly lagging: these are some of the things on a long list of possible database performance issues. How can you figure out why your MySQL installation isn’t …

This guide will get you up and running with how to identify the bottleneck queries using the excellent tool pt-query-digest. You will learn how to use and analyze the output returned by pt-query-digest. You will also learn some differences between slow query logging in various MySQL versions. Later on in the post I will also show you how to make use of the extra diagnostic data available with Percona Server.

The post Profiling your slow queries using pt-query-digest and some love from Percona Server appeared first on ovais.tariq.

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 and choose indexes and it could really be picking up a wrong index simply because of the wrong estimate. You...

The post When EXPLAIN estimates can go wrong! appeared first on ovais.tariq.