April 16, 2014

Changing an async slave of a PXC cluster to a new Master using 5.6 and GTID

Before Percona XtraBackup 2.1.7 and Percona XtraDB Cluster 5.6.15-25.3, rsync was the only SST method supporting GTID in the way that it was possible to move an asynchronous slave from one Galera node to another one (related bug). Indeed, previous versions of Percona XtraBackup didn’t copy any binary log and due to that, moving the […]

High-availability options for MySQL, October 2013 update

The technologies allowing to build highly-available (HA) MySQL solutions are in constant evolution and they cover very different needs and use cases. In order to help people choose the best HA solution for their needs, we decided, Jay Janssen and I, to publish, on a regular basis (hopefully, this is the first), an update on […]

Enabling crash-safe slaves with MySQL 5.6

Being able to configure slaves to be crash-safe is one of the major improvements of MySQL 5.6 with regards to replication. However we noticed confusion on how to enable this feature correctly, so let’s clarify how it should be done. In short 1. Stop MySQL on slave 2. Add relay_log_info_repository = TABLE and relay_log_recovery = […]

Another reason why SQL_SLAVE_SKIP_COUNTER is bad in MySQL

It is everywhere in the world of MySQL that if your replication is broken because an event caused a duplicate key or a row was not found and it cannot be updated or deleted, then you can use ‘ STOP SLAVE; SET GLOBAL SQL_SLAVE_SKIP_COUNTER=1; START SLAVE; ’ and be done with it. In some cases this is fine and you can repair the […]

Changing an async slave of a PXC cluster to a new Master

Async and PXC A common question I get about Percona XtraDB Cluster is if you can mix it with asynchronous replication, and the answer is yes!  You can pick any node in your cluster and it can either be either a slave or a master just like any other regular MySQL standalone server (Just be […]

How to create/restore a slave using GTID replication in MySQL 5.6

MySQL 5.6 is GA! Now we have new things to play with and in my personal opinion the most interesting one is the new Global Transaction ID (GTID) support in replication. This post is not an explanation of what is GTID and how it works internally because there are many documents about that: http://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html One […]

How to lag a slave behind to avoid a disaster

MySQL Replication is useful and easy to setup. It is used for very different purposes. For example: split read and writes run data mining or reporting processes on them disaster recovery Is important to mention that a replication server is not a backup by itself. A mistake on the master, for example a DROP DATABASE […]

How to know if you’re updating Slave you should not ?

When replication runs out of sync first question you often ask is if someone could be writing to the slave. Of course there is read_only setting which is good to set in the slave but it is not set always and also users with SUPER privilege bypass it. Looking into binary log is obvious choice […]

Three ways to know when a MySQL slave is about to start lagging

The trouble with slave lag is that you often can’t see it coming. Especially if the slave’s load is pretty uniform, a slave that’s at 90% of its capacity to keep up with the master can be indistinguishable from one that’s at 5% of its capacity. So how can you tell when your slave is […]

Updated msl (microslow) patch, installation walk-through!

For a couple of months there have been no updates to our msl patch, however recently I managed some time to change this. The functionality was extended a little bit and what’s even more important the patch is available for all the recent MySQL releases. To remind anyone who has not yet come across this […]