Reconfiguring replication has always been a challenge with MySQL. Each time the replication topology has to be changed, the process is tedious and error-prone because finding the correct binlog position is not straightforward at all. Global Transaction IDs (GTIDs) introduced in MySQL 5.6 aim at solving this annoying issue.

The idea is quite simple: each transaction is associated with a unique identifier shared by all servers in a given replication topology. Now reconfiguring replication is easy as the correct binlog position can be automatically calculated by the server.

Awesome? Yes it is! However GTIDs are also changing a lot of things in how we can perform operations on replication. For instance, skipping transactions is a bit more difficult. Or you can get bitten by …

Reconfiguring replication has always been a challenge with MySQL. Each time the replication topology has to be changed, the process is tedious and error-prone because finding the correct binlog position is not straightforward at all. Global Transaction IDs (GTIDs) introduced in MySQL 5.6 aim at solving this annoying issue.

The idea is quite simple: each transaction is associated with a unique identifier shared by all servers in a given replication topology. Now reconfiguring replication is easy as the correct binlog position can be automatically calculated by the server.

Awesome? Yes it is! However GTIDs are also changing a lot of things in how we can perform operations on replication. For instance, skipping transactions is a bit more difficult. Or you can get bitten by …

It’s been three months since we announced anything for Percona Cloud Tools, not because we’ve been idle but because we’ve been so busy the time flew by!  Here’s the TL;DR to pique your interest:

• EXPLAIN queries in real-time through the web app
• Query Analytics for Performance Schema
• Dashboards: customizable, shared groups of charts
• Install and upgrade the agent with 1 command line
• Unified UI: same time range, same host wherever you go

Percona Cloud Tools for MySQL is a hosted service providing access to query performance insights for all MySQL uses. After a brief setup, unlock new information about your database and how to improve your applications. There’s a lot more, but let’s just look at these five new features…

EXPLAIN queries in real-time through the web app

ScaleArc hired Percona to benchmark failover times for the ScaleArc database traffic management software in different scenarios. We tested failover times for various clustered setups, where ScaleArc itself was the load balancer for the cluster. These tests complement other performance tests on the ScaleArc software – sysbench testing for latency and testing for WordPress acceleration.

We tested failover times for Percona XtraDB Cluster (PXC) and MHA (any traditional MySQL replication-based solution works pretty much the same way).

In each case, we tested failover with a rate limited …

Twice each year members of the global open-source community converge on London in November and Santa Clara in April to network with, and learn from, some of the world’s most experienced and accomplished system architects, developers and DBAs.

And now it’s time for YOU to give back to this diverse and growing MySQL community. The Call for Speakers for Percona Live London (Nov. 3-4) closes Aug. 17 and the deadline for submitting talks for the ever-growing Percona Live MySQL Conference and Expo (April 13-16, 2015) expires Nov. 9.

If you like putting things off until the last minute, then it’s time to get to work! Aug. 17 is just two days away and November will be here before you know it (think of how fast summer has gone by already).

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Diablo Technologies engaged Percona to benchmark IBM eXFlash™ DIMMs in various aspects. An eXFlash™ DIMM itself is quite an interesting piece of technology. In a nutshell, it’s flash storage, which you can put in the memory DIMM slots. Enabled by Diablo’s Memory Channel Storage™ technology, this practically means low latency and some unique performance characteristics.

These devices are special, because their full performance potential is unlocked by using multiple devices to leverage the parallelism of the memory subsystem. In a modern CPU there is more than one memory controller (4 is typical nowadays) and spreading eXFlash™ DIMMs across them will provide maximum performance. There are quite some details about the device that are omitted in this post, they can be found in this redbook.

Diablo technologies also provided us a …

Martin Arrieta and I gave an online presentation last week on “Putting MySQL Fabric To Use.” If you missed it, you can find a recording and the slides here, and the vagrant environment we used plus a transcript of the commands we ran here (be sure to check out the ‘sharding’ branch, as that’s what we used during the webinar).

Thank you all for attending and asking interesting questions. We were unable to answer all of them in the scheduled time, so here are our replies to all the questions.

What is GTID? And how does it relate to MySQL Fabric?
GTID stands for Global …

I will be presenting two webinars in August:

• Aug 6, 10 a.m. PDT: Advanced Query Tuning in MySQL 5.6 and Beyond
• Aug 13, 10 a.m. PDT:  Using Performance Schema to Monitor and Troubleshoot MySQL 5.6

This Wednesday’s webinar on advanced MySQL query tuning will be focused on tuning the “usual suspects”: queries with “Group By”, “Order By” and subqueries; those query types are usually perform bad in MySQL and add an additional load as MySQL may need to create a temporary table(s) or perform a filesort. New this year: I will talk more about new MySQL …

As we know different storage engines in MySQL have different file structures. Every table in MySQL 5.6 must have a .frm file in the database directory matching the table name. But where the rest of the data resides depends on the storage engine.

For MyISAM we have .MYI and .MYD files in the database directory (unless special settings are in place); for InnoDB we might have data stored in the single table space (typically ibdata1 in the database directory) or as file per table (or better said file per partition) producing a single file with .ibd extension for each table/partition. TokuDB as of this version (7.1.7) has its own innovative approach to storing the table contents.

I have created the table in the database test having the following structure:

CREATE TABLE `mytable` (
  `id` int(10) unsigned NOT NULL,
  `c` varchar(15) NOT NULL, …

One of the common causes of downtime with MySQL is running out of connections. Have you ever seen this error? “ERROR 1040 (00000): Too many connections.” If you’re working with MySQL long enough you surely have. This is quite a nasty error as it might cause complete downtime… transient errors with successful transactions mixed with failing ones as well as only some processes stopping to run properly causing various kinds of effects if not monitored properly.

There are number of causes for running out of connections, the most common ones involving when the Web/App server is creating unexpectedly large numbers of connections due to a miss-configuration or some script/application leaking connections or creating too many connections in error.

The solution I see some people employ is just to increase max_connections to some very high number so MySQL “never” runs out of connections. This however can cause …