10 Apr

What is the proper size of InnoDB logs?

In one of my previous posts, "How to resize InnoDB logs?", I gave the advice on how to safely change the size of transaction logs. This time, I will explain why doing it may become necessary.

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04 Apr

How to selectively kill queries in MySQL?

For as long as it is only about a few of them, it is as simple as looking at the SHOW PROCESSLIST output for thread identifiers to kill. They can be found in the first column called Id. These values can be passed to KILL thread_id command in MySQL. The problems appear with more complex scenarios. What if one needs to terminate all queries running longer than ten seconds? Doing copy&paste; repetitively could take a lot of time with twenty or so candidate threads. This can be done much more efficiently.

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04 Apr

How to resize InnoDB logs?

If for any reason you need to change the size of InnoDB log files (also known as transaction logs), but not sure how to do it, this post will guide you through the steps.

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02 Apr

Can COUNT(*) be used in MySQL on InnoDB tables?

COUNT() function returns a number of rows returned by a query. In a popular opinion COUNT(*) should not be used on InnoDB tables, but this is only half true.

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01 Apr

How to find configuration file MySQL uses?

A customer called me today asking for help with locating the configuration file used by one of their production MySQL instances. From the description I was given it appeared that their server had at least six different copies of my.cnf file in different locations on disk. And all were similar enough that each could actually be the one. All superfluous files were the result of a bit negligent system administration. So what turned to be the quickest and the least destructive way to find the correct one?

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