We all know disk based temporary tables are bad and you should try to have implicit temporary tables created in memory where possible, do to the fact that you should increase tmp_table_size to appropriate value and avoid using blob/text columns which force table creation on the disk because MEMORY storage engine does not support […]Read more
As you might know while running GROUP BY and some other kinds of queries MySQL needs to create temporary tables, which can be created in memory, using MEMORY storage engine or can be created on disk as MYISAM tables. Which one will be used depends on the allowed tmp_table_size and also by […]Read more
In my Webinar on Using Percona Monitoring and Management (PMM) for MySQL Troubleshooting, I showed how to use direct queries to ClickHouse for advanced query analysis tasks. In the followup Webinar Q&A, I promised to describe it in more detail and share some queries, so here it goes.
PMM uses ClickHouse to store query performance […]
I was recently faced with a real issue about completely exhausting the disk space on MySQL. This was a serious issue because of the continuous outages of the service, as the customer had to constantly restart the server and wait for the next outage.
What was happening? In this article, I’m going to explain it […]
In this blog post, I’ll examine when looking at raw MySQL query logs can be more useful than working with tools that only have summary data.
In my previous blog post, I wrote about analyzing MySQL Slow Query Logs with ClickHouse and ClickTail. One of the follow-up questions I got is when do you […]