April 19, 2014

Introducing backup locks in Percona Server

TL;DR version: The backup locks feature introduced in Percona Server 5.6.16-64.0 is a lightweight alternative to FLUSH TABLES WITH READ LOCK and can be used to take both physical and logical backups with less downtime on busy servers. To employ the feature with mysqldump, use mysqldump –lock-for-backup –single-transaction. The next release of Percona XtraBackup will […]

Innodb Table Locks

Innodb uses row level locks right ? So if you see locked tables reported in SHOW ENGINE INNODB STATUS you might be confused and rightfully so as Innodb table locking is a bit more complicated than traditional MyISAM table locks. Let me start with some examples. First lets run SELECT Query:

As you can […]

How fast is FLUSH TABLES WITH READ LOCK?

A week or so ago at the MySQL conference, I visited one of the backup vendors in the Expo Hall. I started to chat with them about their MySQL backup product. One of the representatives told me that their backup product uses FLUSH TABLES WITH READ LOCK, which he admitted takes a global lock on […]

SELECT LOCK IN SHARE MODE and FOR UPDATE

Baron wrote nice article comparing locking hints in MySQL and SQL Server. In MySQL/Innodb LOCK IN SHARE MODE and SELECT FOR UPDATE are more than hints. Behavior will be different from normal SELECT statements. Here is simple example:

INSERT INTO … SELECT Performance with Innodb tables.

Everyone using Innodb tables probably got use to the fact Innodb tables perform non locking reads, meaning unless you use some modifiers such as LOCK IN SHARE MODE or FOR UPDATE, SELECT statements will not lock any rows while running. This is generally correct, however there a notable exception – INSERT INTO table1 SELECT * […]

New mydumper 0.6.1 release offers performance and usability features

One of the tasks within Percona Remote DBA is to ensure we have reliable backups with minimal impact. To accomplish this, one of the tools our team uses is called mydumper. We use mydumper for logical backups because of several nice features. Some of them are: multithreaded, producing very fast backups compared to mysqldump almost […]

Measuring Max Replication Throughput on Percona XtraDB Cluster with wsrep_desync

Checking throughput with async MySQL replication Replication throughput is the measure of just how fast the slaves can apply replication (at least by my definition).  In MySQL async replication this is important to know because the single-threaded apply nature of async replication can be a write performance bottleneck.  In a production system, we can tell […]

Taking backups on Percona XtraDB Cluster (without stalls!)

I occasionally see customers who are taking backups from their PXC clusters that complain that the cluster “stalls” during the backup.  As I wrote about in a previous blog post, often these stalls are really just Flow Control.  But why would a backup cause Flow control? Most backups I know of (even Percona XtraBackup) take […]

MySQL Security Webinar: Follow-up Q&A

Thanks to everyone who attended last week’s webinar on MySQL security; hopefully you’ve all gone out and set SELinux to enforcing mode if you weren’t already running that way. If you weren’t able to attend, the recording and slides are available for viewing/download. But now, without further ado, here are the questions which we didn’t […]

Announcing Percona XtraBackup 2.0.5

Percona is glad to announce the release of Percona XtraBackup 2.0.5 on January 23rd, 2012. Downloads are available from our download site here and Percona Software Repositories. This release is the current GA (Generally Available) stable release in the 2.0 series. New Features: New option –defaults-extra-file has been introduced. This option specifies from what extra file to read […]