May 20, 2013

Is Synchronous Replication right for your app?

May 14, 2013 By 16 Comments

I talk with lot of people who are really interested in Percona XtraDB Cluster (PXC) and mostly they are interested in PXC as a high-availability solution.  But, what they tend not to think too much about is if moving from async to synchronous replication is right for their application or not. Facts about Galera replication [...]

Filed Under: MySQL, Percona Software, XtraDB Cluster Tagged With: , , , , , ,

MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark

March 11, 2013 By 7 Comments

So far most of the benchmarks posted about MySQL 5.6 use the sysbench OLTP workload.  I wanted to test a set of queries which, unlike sysbench, utilize joins.  I also wanted an easily reproducible set of data which is more rich than the simple sysbench table.  The Star Schema Benchmark (SSB) seems ideal for this. [...]

Filed Under: MySQL Tagged With: , , , , ,

InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

This is part 2 in a 3 part series. In part 1, we took a quick look at some initial configuration of InnoDB full-text search and discovered a little bit of quirky behavior; here, we are going to run some queries and compare the result sets. Our hope is that the one of two things [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: , , , , ,

Edge-case behavior of INSERT…ODKU

October 27, 2012 By 6 Comments

A few weeks back, I was working on a customer issue wherein they were observing database performance that dropped through the floor (to the point of an outage) roughly every 4 weeks or so. Nothing special about the environment, the hardware, or the queries; really, the majority of the database was a single table with [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL

Differences between READ-COMMITTED and REPEATABLE-READ transaction isolation levels

August 28, 2012 By 3 Comments

As an instructor with Percona I’m sometimes asked about the differences between the READ COMMITTED and REPEATABLE READ transaction isolation levels.  There are a few differences between READ-COMMITTED and REPEATABLE-READ, and they are all related to locking.

Filed Under: Insight for DBAs, MySQL Tagged With: , , ,

Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks

August 17, 2012 By 17 Comments

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 [...]

Filed Under: MySQL, XtraDB Cluster

Innodb Table Locks

July 31, 2012 By 4 Comments

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 [...]

Filed Under: Insight for DBAs, MySQL

Find and remove duplicate indexes

June 20, 2012 By 9 Comments

Having duplicate keys in our schemas can hurt the performance of our database: They make the optimizer phase slower because MySQL needs to examine more query plans. The storage engine needs to maintain, calculate and update more index statistics DML and even read queries can be slower because MySQL needs update fetch more data to [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL, Percona Software

Secure passwords being insecure

May 27, 2012 By 6 Comments

If you follow the general advices to create secure password the following ones seem to be secure, right? s11P$||!sh&2 pr0&!!ke0 3kj39|!381 The answer to the question is, “it depends on how you use them” Notice that these passwords all contain multiple exclamation points and ampersands which are normally special characters for your shell. The people [...]

Filed Under: Insight for DBAs, MySQL

Statement based replication with Stored Functions, Triggers and Events

December 16, 2011 By 4 Comments

Statement based replication writes the queries that modify data in the Binary Log to replicate them on the slave or to use it as a PITR recovery. Here we will see what is the behavior of the MySQL when it needs to log “not usual” queries like Events, Functions, Stored Procedures, Local Variables, etc. We’ll [...]

Filed Under: MySQL
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