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 [...]
Announcing Percona XtraDB Cluster 5.5.27-23.6
September 7, 2012 By Leave a Comment
Percona is glad to announce the release of Percona XtraDB Cluster on September 7th, 2012. Binaries are available from downloads area or from our software repositories. Features: Percona XtraDB Cluster supports tunable buffer size for fast index creation in InnoDB. This value was calculated based on the merge block size (which was hardcoded to 1 [...]
When is MIN(DATE) != MIN(DATE) ?
September 4, 2012 By 5 Comments
Inspiration for this post is courtesy of a friend and former colleague of mine, Greg Youngblood, who pinged me last week with an interesting MySQL puzzle. He was running Percona Server 5.5.21 with a table structure that looks something like this:
1 2 3 4 5 6 7 8 9 | CREATE TABLE foo ( id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, uid INT UNSIGNED NOT NULL, update_time DATETIME NOT NULL, .... INDEX `uid` (uid, update_time), INDEX `bar` (some_other_columns) .... ) ENGINE=InnoDB; |
When he ran this query:
1 | SELECT MIN(update_time) FROM foo WHERE update_time IS NOT NULL AND update_time <> '0000-00-00 00:00:00'; |
The result came back as 2012-06-22 10:28:16. [...]
Wow. My 6 year old MySQL Bug is finally fixed in MySQL 5.6
August 30, 2012 By 2 Comments
I got the message in the morning today about the bug being fixed in MySQL 5.6.6…. which I reported in Early 2006 (while still being with MySQL) and running MySQL 4.1 I honestly thought this issue was fixed long ago as it was indeed pretty annoying. I must say I’m very impressed with Oracle team [...]
Announcing Percona Server 5.5.27-28.0
August 23, 2012 By 5 Comments
Percona is glad to announce the release of Percona Server 5.5.27-28.0 on August 23rd, 2012 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.5.27, including all the bug fixes in it, Percona Server 5.5.27-28.0 is now the current stable release in the 5.5 series. All of Percona‘s software is open-source and free, all the details of the release can [...]
MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
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 [...]
Filling the tmp partition with persistent connections
August 6, 2012 By 14 Comments
The use of tmpfs/ramfs as /tmp partition is a common trick to improve the performance of on-disk temporary tables. Servers usually have less RAM than disk space so those kind of partitions are very limited in size and there are some cases were we can run out of space. Let’s see one example. We’re running [...]
SQL Injection Questions Followup
July 26, 2012 By 2 Comments
I presented a webinar today about SQL Injection, to try to clear up some of the misconceptions that many other blogs and articles have about this security risk. You can register for the webinar even now that I’ve presented it, and you’ll be emailed a link to the recording, which will be available soon. During [...]
Percona XtraDB Cluster: Failure Scenarios with only 2 nodes
July 25, 2012 By 6 Comments
During the design period of a new cluster, it is always advised to have at least 3 nodes (this is the case with PXC but it’s also the same with PRM). But why and what are the risks ? The goal of having more than 2 nodes, in fact an odd number is recommended in [...]
Comparing Percona XtraDB Cluster with Semi-Sync replication Cross-WAN
June 14, 2012 By 7 Comments
I have a customer who is considering Percona XtraDB Cluster (PXC) in a two colo WAN environment. They wanted me to do a test comparing PXC against semi-synchronous replication to see how they stack up against each other. Test Environment The test environment included AWS EC2 nodes in US-East and US-West (Oregon). The ping RTT latency [...]
