lefred's blog

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MySQL Memory Consumption and Open Prepare Statements

Today I read the nice post of Bhuvanesh on the memory leak issue they experienced with MySQL. In fact when you read the post, you realize that MySQL was just following the parameters that were setup (the default of max_prepare_stmt_count is 16382 even on 5.6). I’m still convinced that the problem should be resolved in the application even if the … Read More

MySQL: when will the password of my users expire ?

Has you may already know, in MySQL it is possible to set an expiration period for passwords. It’s not always obvious to see when the password will expire. And most of the time if you don’t pay much attention you will get something like this: ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this … Read More

MySQL: size of your tables – tricks and tips

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

How to know if a user never connected to the MySQL server since last boot ?

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

MySQL Router HA with Keepalived

After having explained how to achieve HA for MySQL Router for people who doesn’t want to install the MySQL Router on the application servers and after having illustrated how to use Pacemaker, this article explains how to setup HA for MySQL Router using keepalived. Keepalived is very popular, maybe because it’s also very easy to use. We can of course … Read More