August 28, 2014

Replication in MySQL 5.6: GTIDs benefits and limitations – Part 1

Global Transactions Identifiers are one of the new features regarding replication in MySQL 5.6. They open up a lot of opportunities to make the life of DBAs much easier when having to maintain servers under a specific replication topology. However you should keep in mind some limitations of the current implementation. This post is the […]

Percona XtraDB Cluster for MySQL and encrypted Galera replication

Few people realize that Galera/Percona XtraDB (PXC) replication can be encrypted via SSL for secure transfer of your replicated data.  Setting this up is actually quite easy to do and probably will look familiar to a lot of people. Setting up SSL and Galera Create and propagate a single key/cert pair First, we create a […]

Disconnecting a replication slave is easier with MySQL 5.5+ (RESET SLAVE vs. RESET SLAVE ALL)

It’s not uncommon to promote a server from slave to master. One of the key things to protect your data integrity is to make sure that the promoted slave is permanently disconnected from its old master. If not, it may get writes from the old master, which can cause all kinds of data corruption. MySQL […]

Repair MySQL 5.6 GTID replication by injecting empty transactions

In a previous post I explained how to repair MySQL 5.6 GTID replication using two different methods. I didn’t mention the famous SET GLOBAL SQL_SLAVE_SKIP_COUNTER = n for a simple reason, it doesn’t work anymore if you are using MySQL GTID. Then the question is: Is there any easy way to skip a single transaction? […]

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 […]

Replication checksums in MySQL 5.6

MySQL 5.6 has an impressive list of improvements. Among them, replication checksums caught my attention as it seems that many people misunderstand the real added value of this new feature. I heard people think that with replication checksums, data integrity between the master and its replicas is now enforced. As we’ll see, it’s not that […]

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 does MySQL Replication really work?

While we do have many blog posts on replication on our blog, such as on replication being single-threaded, on semi-synchronous replication or on estimating replication capacity, I don’t think we have one that covers the very basics of how MySQL replication really works on the high level. Or it’s been so long ago I can’t […]

How Does Semisynchronous MySQL Replication Work?

With the recent release of Percona XtraDB Cluster, I am increasingly being asked about MySQL’s semi-synchronous replication. I find that there are often a number of misconceptions about how semi-synchronous replication really works. I think it is very important to understand what guarantees you actually get with semi-synchronous replication, and what you don’t get. The […]

Actively monitoring replication connectivity with MySQL’s heartbeat

Until MySQL 5.5 the only variable used to identify a network connectivity problem between Master and Slave was slave-net-timeout. This variable specifies the number of seconds to wait for more Binary Logs events from the master before abort the connection and establish it again. With a default value of 3600 this has been a historically […]