September 2, 2014

Percona XtraDB Cluster 5.5.33-23.7.6 is now available

Percona is glad to announce the release of Percona XtraDB Cluster 5.5.33-23.7.6 on September 18, 2013. Binaries are available from the downloads area or from our software repositories. New Features: Default State Snapshot Transfer method, defined in wsrep_sst_method variable has been changed from mysqldump to rsync. New wsrep_reject_queries variable has been implemented that can be […]

Crash-resistant replication: How to avoid MySQL replication errors

Percona Server’s “crash-resistant replication” feature is useful in versions 5.1 through 5.5. However, in Percona Server 5.6 it’s replaced with Oracle MySQL 5.6′s “crash safe replication” feature, which has it’s own implementation (you can read more about it here). A MySQL slave normally stores its position in files master.info and relay-log.info which are updated by […]

trx descriptors: MySQL performance improvements in Percona Server 5.5.30-30.2

One major problem in terms of MySQL performance that still stands in the way of InnoDB scalability is the trx_list scan on consistent read view creation. It was originally reported as a part of MySQL bug #49169 and can be described as follows. Whenever a connection wants to create a consistent read, it has to […]

Investigating MySQL Replication Latency in Percona XtraDB Cluster

I was curious to check how Percona XtraDB Cluster behaves when it comes to MySQL replication latency — or better yet, call it data propagation latency. It was interesting to see whenever I can get stale data reads from other cluster nodes after write performed to some specific node. To test it I wrote quite a […]

Understanding Multi-node writing conflict metrics in Percona XtraDB Cluster and Galera

I have addressed previously how multi-node writing causes unexpected deadlocks in PXC, at least, it is unexpected unless you know how Galera replication works.  This is a complicated topic and I personally feel like I’m only just starting to wrap my head around it. The magic of Galera replication The short of it is that Galera […]

Automation: A case for synchronous replication

Just yesterday I wrote about math of automatic failover today I’ll share my thoughts about what makes MySQL failover different from many other components and why asynchronous nature of standard replication solution is causing problems with it. Lets first think about properties of simple components we fail over – web servers, application servers etc. We […]

Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks

Percona XtraDB Cluster (PXC) and the technology it uses (Galera) is an exciting alternative to traditional MySQL replication.  For those who don’t know, it gives you: Fully Synchronous replication with a write latency increase equivalent to a ping RTT to the furthest node Automatic cluster synchronization, both incremental and full restores The ability to read […]

Comparing Percona XtraDB Cluster with Semi-Sync replication Cross-WAN

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 […]

Percona XtraDB Cluster Feature 2: Multi-Master replication

This is about the second great feature – Multi-Master replication, what you get with Percona XtraDB Cluster. It is recommended you get familiar with general architecture of the cluster, described on the previous post. By Multi-Master I mean the ability to write to any node in your cluster and do not worry that eventually you […]

ACTIVE with Locks – Now thats a problem !

One of item I always look at SHOW ENGINE INNODB STATUS to see if there are any transactions spending very long time in ACTIVE state. In the perfect world if you’re running online system you should not see transactions spending more than couple of seconds in ACTIVE state. Especially ACTIVE transactions which do not currently […]