This is a recurrent question made by our MySQL Support customers: How can I audit the login attempts in MySQL? Logging all the attempts or just the failed ones is a very important task on some scenarios. Unfortunately there are not too many audit capabilities in MySQL Community so the first option to audit MySQL’s […]
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How easy is it to identify and debug Percona XtraDB Cluster replication problem ? If you are using PXC, you may have already seen in your datadirectory several log files starting with GRA_ Those files correspond to a replication failure. That means the slave thread was not able to apply one transaction. For each of […]
LVM snapshots is one powerful way of taking a consistent backup of your MySQL databases – but did you know that you can now restore directly from a snapshot (and binary logs for point in time recovery) in case of that ‘Oops’ moment? Let me show you quickly how. This howto assumes that you already […]
It is no secret that bugs related to multithreading–deadlocks, data races, starvations etc–have a big impact on application’s stability and are at the same time hard to find due to their nondeterministic nature. Any tool that makes finding such bugs easier, preferably before anybody is aware of their existence, is very welcome.
If you need to change MySQL’s innodb_log_file_size parameter (see How to calculate a good InnoDB log file size), you can’t just change the parameter in the my.cnf file and restart the server. If you do, InnoDB will refuse to start because the existing log files don’t match the configured size. You need to shut the […]
I wrote about MySQL Error Messages before and as you might guess I’m not very happy with quality for error messages it produces. Now I’m revisiting this subject with couple of more annoying examples I ran into during last couple of days.
mysql> drop database test;
ERROR 1010 (HY000): Error dropping database (can't rmdir './test/', errno: 17)
Xaprb (Baron) recently blogged about how InnoDB performs a checkpoint , I thought it might be useful to explain another important mechanism that affects both response time and throughput – The transaction log.
We have had been using Akismet as our primary antispam tool for quite a while.Â It works okay, but recently we have started to get the feeling we need a better solution. With Akismet were still burdened with a lot of manual moderation for false negatives and scanning detected spam for false positives (can’t say […]
Introduction When people think about Perconaâ€™s microslow patch immediately a question arises how much logging impacts on performance. When we do performance audit often we log every query to find not only slow queries. A query may take less than a second to execute, but a huge number of such queries may significantly load a […]
Have you ever seen the replication stopped with message like this: Last_Error: Could not parse relay log event entry. The possible reasons are: the master’s binary log is corrupted (you can check this by running ‘mysqlbinlog’ on the binary log), the slave’s relay log is corrupted (you can check this by running ‘mysqlbinlog’ on the […]