The latest from the MySQL community

Thanks to all who attended my webinar yesterday.  The slides and recording are available on the webinar’s page.  I was a bit overwhelmed with the amount of questions that came in and I’ll try to answer them the best I can here.

Q: Does Percona XtraDB Cluster support writing to multiple master?

Yes, it does.  However, locks are not held on all nodes while a transaction is in progress, so there is a possibility for conflicts between simultaneous writes on different nodes.  Certification is the process that Galera uses to protect your data integrity, and the problem is pushed back to the application to handle in the form of deadlock errors.   As long as you understand this and the conditions where you may see more deadlocks (and your application can properly handle them), multi-node …

ClusterControl for Percona XtraDB Cluster is now available in three different versions thanks to our partnership with Severalnines. ClusterControl will make it simpler to manage and monitor Percona XtraDB Cluster, MySQL Cluster, MySQL Replication, or MySQL Galera.

I am very excited about our GA release of Percona XtraDB Cluster 5.6 last week. As Vadim described in his blog post announcing the release, we have brought together the benefits of Percona Server 5.6, Percona XtraBackup and Galera 3 to create a drop-in compatible, open source, state-of-the-art high availability MySQL clustering solution. We could not have done it without the close cooperation and help of our partners at Codership. To learn more, join us on February …

Percona is pleased to announce the first General Availability release of the leading open source High Availability solution for MySQL, Percona XtraDB Cluster 5.6 on January 30, 2014. Binaries are available from downloads area or from our software repositories.

Percona XtraDB Cluster 5.6
Percona XtraDB Cluster 5.6 is an active/active cluster solution for High Availability (HA) MySQL that delivers performance and MySQL-based cluster management features available nowhere else. This free, open source solution combines …

This is a followup to Jay Janssen’s October post, “Using keepalived for HA on top of Percona XtraDB Cluster.” We got a request recently where the customer has 2 VIPs (Virtual IP addresses), one for reader and one for a writer for a cluster of 3 nodes. They wanted to keep it simple, with low latency and does not require an external node resource like HaProxy would.

keepalived is a simple load balancer with HA capabilities, which means it can proxy TCP services behind it and at the same time, keep itself highly available using VRRP as failover mechanism. This post is about taking advantage of the …

I’ve been blogging a lot about some of the new things you can expect with Percona XtraDB Cluster 5.6 and Galera 3.x – and GA is coming …

Most technologies achieving high-availability for MySQL need a load-balancer to spread the client connections to a valid database host, even the Tungsten special connector can be seen as a sophisticated load-balancer. People often use hardware load balancer or software solution like haproxy. In both cases, in order to avoid having a single point of failure, multiple load balancers must be used. Load balancers have two drawbacks: they increase network latency and/or they add a validation check load on the database servers. The increased network latency is obvious in the case of standalone load balancers where you must first connect to the load balancer which then completes the request by connecting to one of the database servers. Some workloads like reporting/adhoc queries are not affected by a small increase of latency but other workloads like oltp processing and real-time logging are. Each load balancers must also check regularly if the database …

Gcache and IST

The Gcache is a memory-based cache of recent Galera transactions that is local to each node in a cluster.  If a node leaves and rejoins the cluster, it can use the gcache from another node that stayed in the cluster (i.e., its donor node) to fetch the transactions it missed (IST) as opposed to doing a full state snapshot transfer (SST).  However, there are a few nuances that are not obvious to the beginner:

• The Gcache is lost when a node restarts
• The Gcache is fixed size and implemented as a LRU.  Once it is full, older transactions roll off.
• Donor selection is made irregardless of the gcache state
• If the given donor for a restarting node doesn’t have all transactions needed, a full SST (read: full backup) is done instead
• Until recent developments, there was no way to tell what, precisely, was in the Gcache.

So, with (somewhat) …

A decade ago MySQL folks were in love with the concept of a relay slave for MySQL high availability across data centers.  A relay is a single slave in a remote data center that receives replication from the global master and, in turn, replicates to all the other local slaves in that data center.  This saved a lot of bandwidth, especially back in the days before memcached when scaling reads meant lots of slaves.  Sending 20 copies of your replication stream cross-WAN gets expensive.

In Galera and Percona XtraDB Cluster (PXC), by default when a transaction commits on a given node it is sent to every other node in the cluster from that node.  That is, the actual writeset payload (the RBR events) are sent over the network to every other node, so the bandwidth to replicate is roughly:

<writeset size> * …

Percona is glad to announce the release of Percona XtraDB Cluster 5.5.34-25.9 on December 4, 2013. Binaries are available from the downloads area or from our software repositories.

Based on Percona Server 5.5.34-32.0 including all the bug fixes in it, Galera Replicator and on Codership wsrep API 5.5.34-25.9, Percona XtraDB Cluster …

I get a lot of questions about Percona XtraDB Cluster 5.6 (PXC 5.6), specifically about whether such and such MySQL 5.6 Community Edition feature is in PXC 5.6.  The short answer is: yes, all features in community MySQL 5.6 are in Percona Server 5.6 and, in turn, are in PXC 5.6.  Whether or not the new feature is useful in 5.6 really depends on how useful it is in general with Galera.

I thought it would be useful to highlight a few features and try to show them working:

Innodb Fulltext Indexes

Yes, FTS works in Innodb in 5.6, so why wouldn’t it work in PXC 5.6?  To test this I used the Sakila database , which contains a single table with FULLTEXT.  In the sakila-schema.sql file, it is still designated a MyISAM table: