While most of the talk recently has mostly been around the new changes in MySQL 5.6 (and that is understandable), I have had lately some very interesting cases to deal with, with respect to the Metadata Locking related changes that were introduced in MySQL 5.5.3. It appears that the implications of Metadata Locking have not [...]
Read/Write Splitting with PHP Webinar Questions Followup
January 23, 2013 By 4 Comments
Today I gave a presentation on “Read/Write Splitting with PHP” for Percona Webinars. If you missed it, you can still register to view the recording and my slides. Thanks to everyone who attended, and especially to folks who asked the great questions. I answered as many as I could during the session, but here are [...]
How to STOP SLAVE on Amazon RDS read replica
December 20, 2012 By 4 Comments
We are doing a migration from Amazon RDS to EC2 with a customer. This, unfortunately, involves some downtime – if you are an RDS user, you probably know you can’t replicate an RDS instance to an external server (or even EC2). While it is annoying, this post isn’t going to be a rant on how [...]
Percona XtraDB Cluster (PXC): what about GRA_*.log files ?
December 19, 2012 By Leave a Comment
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 [...]
Announcing Percona Playback 0.5
November 26, 2012 By
Percona is glad to announce the release of Percona Playback 0.5 on November 26th, 2012. Downloads are available from our download site and Percona Software Repositories. Percona Playback is a tool for replaying the load of one database server to another. Currently it can read queries from MySQL query-log and tcpdump files and run them [...]
Concatenating MyISAM files
November 19, 2012 By 5 Comments
Recently, I found myself involved in the migration of a large read-only InnoDB database to MyISAM (eventually packed). The only issue was that for one of the table, we were talking of 5 TB of data, 23B rows. Not small… I calculated that with something like insert into MyISAM_table… select * from Innodb_table… would take [...]
Knowing what pt-online-schema-change will do
November 1, 2012 By 1 Comment
pt-online-schema-change is simple to use, but internally it is complex. Baron’s webinar about pt-online-schema-change hinted at several of the tool’s complexities. Consequently, users often want to know before making changes what pt-online-schema-change will do when it runs. The tool has two options to help answer this question: –dry-run and –print. When ran with –dry-run and –print, pt-online-schema-change changes nothing [...]
Edge-case behavior of INSERT…ODKU
October 27, 2012 By 6 Comments
A few weeks back, I was working on a customer issue wherein they were observing database performance that dropped through the floor (to the point of an outage) roughly every 4 weeks or so. Nothing special about the environment, the hardware, or the queries; really, the majority of the database was a single table with [...]
Recovering from a bad UPDATE statement
October 19, 2012 By 5 Comments
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:
1 2 3 4 5 6 | CREATE TABLE `t1` ( `c1` int(11) NOT NULL AUTO_INCREMENT, `c2` varchar(10) NOT NULL, PRIMARY KEY (`c1`) ) ENGINE=InnoDB; INSERT INTO `t1` (`c2`) VALUES ('michael'), ('peter'), ('aamina'); |
We run an accidental UPDATE statement that [...]
MySQL 5.6.7-RC in tpcc-mysql benchmark
October 8, 2012 By 21 Comments
MySQL 5.6.7 RC is there, so I decided to test how it performs in tpcc-mysql workload from both performance and stability standpoints. I can’t say that my experience was totally flawless, I bumped into two bugs: MySQL 5.6.7 locks itself on CREATE INDEX MySQL 5.6.7-rc crashed under tpcc-mysql workload But at the end, is not [...]
