We saw in the previous post that MySQL likes memory. We also saw how to perform operating system checks and some configuration changes for Swap and NUMA. Today, we will check what MySQL server can tell us about its memory usage. Introduced in MySQL 5.7 and enabled by default in MySQL 8.0, the Performance_Schema‘s Memory instrumentation allows us to have … Read More
Many of you already know how to retrieve the size of your dataset, schemas and tables in MySQL. To summarize, below are the different queries you can run: Dataset Size I the past I was using something like this : But now with sys schema being installed by default, I encourage you to use some of the formatting functions provided … Read More
If you are a MySQL DBA for a long time (like me), it’s very complicated to get rid of bad habits. One of them I really need to change is the way to retrieve the list of all the running queries (processlist). Usually, I use SHOW FULL PROCESSLIST which is very convenient, but like querying the Information_Schema, this statement has … Read More
Performance_Schema is used most of the time to get metrics about queries and connections. But it can also provide other very useful information. So today, I will show you how you can see a list of users that didn’t connect to MySQL since we restarted it (since last reboot). SELECT DISTINCT mu.user FROM mysql.user mu LEFT JOIN performance_schema.users psu ON … Read More
At the end we all agree that what really matters is the Query Response Time, isn’t it ? MySQL 8.0 engineers have added more visibility in the summary tables as explained in this previous post. But to add more details, now the Performance_Schema also collects the statements latency and provide their distribution thanks to the collected histogram data. Two tables … Read More
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