I talk with lot of people who are really interested in Percona XtraDB Cluster (PXC) and mostly they are interested in PXC as a high-availability solution. But, what they tend not to think too much about is if moving from async to synchronous replication is right for their application or not. Facts about Galera replication [...]
About a month ago, we held a bug raffle for Percona Toolkit 2.1.9. The turnout was good and the resulting release is worth upgrading to, especially if you were affected by the backwards-incompatible changes to pt-heartbeat in 2.1.8. Here are the release notes for Percona Toolkit 2.1.9 which highlight the bugs fixed: Percona Toolkit 2.1.9 has been released. [...]
MySQL 5.6 has an impressive list of improvements. Among them, replication checksums caught my attention as it seems that many people misunderstand the real added value of this new feature. I heard people think that with replication checksums, data integrity between the master and its replicas is now enforced. As we’ll see, it’s not that [...]
Recently some of my fellow Perconians and I have noticed a bit of an uptick in customer cases featuring the following error message:
SQLSTATE[HY000]  Can't create a new thread (errno 11); if you are not
out of available memory, you can consult the manual for a possible OS-dependent bug.
The canonical solution to this issue, if you do a bit of Googling, is to increase the number of processes / threads available to the MySQL user, typically by adding a [...]
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 [...]
Did you just run an UPDATE against your 10 million row users table without a WHERE clause? Did you know that in MySQL 5.5 that sometimes you can recover from a bad UPDATE statement? This is possible if you are running in binlog_format=ROW ! Imagine this scenario:
CREATE TABLE `t1` (
`c1` int(11) NOT NULL AUTO_INCREMENT,
`c2` varchar(10) NOT NULL,
PRIMARY KEY (`c1`)
INSERT INTO `t1` (`c2`) VALUES ('michael'), ('peter'), ('aamina');
We run an accidental UPDATE statement that [...]
James Day just posted the great summary of defaults changes in MySQL 5.6 compared to MySQL 5.5 In general there are a lot of good changes and many defaults are now computed instead of hardcoded. Though some of changes are rather puzzling for me. Lets go over them: back_log = 50 + ( max_connections / [...]
Ever ran into a situation where you saw “some important variable you really needed to know about=<optimized out>” while debugging?
As an instructor with Percona I’m sometimes asked about the differences between the READ COMMITTED and REPEATABLE READ transaction isolation levels. There are a few differences between READ-COMMITTED and REPEATABLE-READ, and they are all related to locking.
I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others are better answered in writing anyway. Q: One developer on our team wants to replace longish (25-30) indexed varchars with [...]