This week we discuss changed behavior of variables in MySQL 5.6. In ear candy we talk about a cloud-based service to play with SQL on different databases, and At the Movies is Stewart Smith of Percona talking about MySQL in the Cloud as a Service during Linux Conf Australia in Canberra.

Changed behavior of variables in 5.6
boolean variables can be set to ON/OFF 1/0 TRUE/FALSE

Variables with changes:
log_slave_updates

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With each release, the MySQL database brings you even better performance. To get the most from your MySQL servers, performance tuning is important. And what better route than to take the MySQL for Performance Tuning training course.

In this four-day instructor-led class you will learn to:

• Understand the basics of Performance Tuning
• Use the tools of performance tuning
• Tune the MySQL server instance to improve performance
• Improve performance of tables
• Implement proper Schema Design to improve performance
• Improve the performance of MySQL queries

This course is available as:

• Training-on-Demand: Start training within 24 hrs of registering and follow the course at your own pace and from your own desk.
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Oracle has now launched MySQL-5.6.10-GA, so it is time to come up with some new benchmark results. The test candidates in this benchmark run are

• MySQL-5.5.29
• MySQL-5.6.10
• MariaDB-5.5.28a
• MariaDB-10.0.1

The 5.5 versions are in because I wanted to check for any regressions. In the past we have often seen performance regressions in newer versions which were caused by new features.

This time the benchmark was run on a different box. The main difference is that this box does not have SSD but a high performance RAID-5 with 512M of battery-backed cache. Besides that the machine has 16 cores out of which 12 were used for mysqld and the other 4 for sysbench.

The benchmark uses sysbench-0.5 OLTP with 8 tables and 10G worth of data. InnoDB buffer pool was 16G, InnoDB log group capacity 4G (the maximum for MySQL-5.5). The different disk system required different InnoDB …

When MySQL gets a query, it is the job of the optimizer to find the cheapest way to execute that query. Decisions include access method (range access, table scan, index lookup etc), join order, sorting strategy etc. If we simplify a bit, the optimizer first identifies the different ways to access each table and calculate their cost. After that, the join order is decided.

However, some access methods can only be considered after the join order has been decided and therefore gets special treatment in the MySQL optimizer. For join conditions, e.g. "WHERE table1.col1 = table2.col2",  index lookup can only be used in table2 if table1 is earlier in the join sequence. Another class of access methods is only meaningful for tables that are first in the join order. An example is queries with ORDER BY ... LIMIT. Prior to MySQL 5.6.10 there was a bug in MySQL that made the optimizer choose inefficient execution plans for this query type. …

This week we begin to discuss replication features in MySQL 5.6. Ear Candy is a LOAD DATA INFILE bug and using CSV to get beyond it; At the Movies is Suzan Bond talking about "The Art of Self-Sourcing".

Events
Oracle's doing more MySQL tech tours. These seminars will be in the mornings, and are free. They will be on:
Tuesday, February 19th in Petach Tikva, Israel
Thursday, February 21st in Oslo and Brussels

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I'm not the only one to have noticed this, but I spent a sufficient amount of time banging my head against a wall finding this out that I thought it important to make more people aware of this.

While trying to validate new database hardware we were seeing some serious performance issues in production.  Most MySQL benchmarks using sysbench or pt-playback couldn't reproduce it, but a simple sysbench 16 threaded filio test on the mysql partition showed about 1/3 the throughput we would expect.   The fact that much of the hardware was new as well as the OS we were using made tracking down the cause difficult (changing from CentOS 5.5 to Scientific Linux 6.)

Finally some of our ops people working on different systems started noticing similar issues, and they uncovered the XFS issue.  Sure enough -- when took existing hardware, upgraded to SL6 and ran the same sysbench filio test we immediately saw a …

With data volumes and user populations growing, its no wonder that database performance is a hot topic in developer and DBA circles.  

Its also no surprise that continued performance improvements were one of the top design goals of the new MySQL 5.6 release which was declared GA on February 5th (note: GA means “Generally Available”, not “Gypsy Approved” @mysqlborat)

And the performance gains haven’t disappointed:

- Dimitri Kravtchuk’s Sysbench tests showed MySQL delivering up to 4x higher performance than the previous 5.5 release.

- Mikael Ronstrom’s testing showed up to 4x better scalability as thread counts rose to 48 and 60 …

Recently we have helped our customer to migrate their entire application stack from one data center to another. Before we were brought on-board, customer had already placed an order for a new set of servers with the new hosting provider. All of them were suppose to be high-end systems – many CPU cores, plenty of RAM and RAID array build on top of SSD drives. As the new machines started being available to us, we began setting up the new environment. At some point it turned out that the new machines were actually slower compared to the several year old systems and their load was much higher under comparable traffic.

We examined several of the new servers and each time the conclusion was that the problems were related poor I/O performance. In the benchmarks a RAID 10 array on Intel SSD 330 Series drives was barely able to achieve 200-300 IOPS in random writes and even that at the cost of …

The MySQL database provides top-level performance. Here are two courses to help you get the most out of your MySQL system.

Troubleshooting MySQL Performance With Sveta Smirnova

This 1 day seminar is an opportunity to interact with Sveta Smirnova, MySQL engineer, expert on MySQL Performance and author of MySQL Troubleshooting.

Sign up for this seminar scheduled for February 28th, 2013 in London, England. 

Sveta will start from basics, working towards more advanced cases that DBAs would usually need years of experience to identify or …

Queries in MySQL, Sphinx and many other database or search engines are typically single-threaded. That is when you issue a single query on your brand new r910 with 32 CPU cores and 16 disks, the maximum that is going to be used to process this query at any given point is 1 CPU core and 1 disk. In fact, only one or the other.

Seriously, if query is CPU intensive, it is only going to be using 3% of the available CPU capacity (for the same 32-core machine). If disk IO intensive – 6% of the available IO capacity (for the 16-disk RAID10 or RAID0 for that matter).

Let me put it another way. If your MySQL or Sphinx query takes 10s to run on a machine with a single CPU core and single disk, putting it on a machine with 32 such cores and 16 such disks will not make it any better.

But you knew this already. Question is – can you do something about it?

In case of Sphinx – indeed you can! And with very little …