When a write query is sent to Percona XtraDB Cluster all the nodes store the writeset on a file called gcache. By default the name of that file is galera.cache and it is stored in the MySQL datadir. This is a very important file, and as usual with the most important variables in MySQL, the default value is not good for high-loaded servers. Let’s see why it’s important and how can we calculate a correct value for the workload of our cluster.

What’s the gcache?
When a node goes out of the cluster (crash or maintenance) it obviously stops receiving changes. When you try to reconnect the node to the cluster the data will be outdated. The joiner node needs to ask a donor to send the changes happened during the downtime.

The donor …

Stored routines give you the ability to create a statement in one application (MySQL) that can be used in multiple client applications that use different programming languages or work on different platforms.

Take the MySQL for Developers course to learn more about stored routines and other key topics. This will build your expertise as a MySQL Developer.

You can take this 5-day instructor-led course as a:

• Live-Virtual Event: Attend a live-event from your own desk, no travel required. Choose from a selection of events already on the schedule to suit different timezones.
• In-Class Event: Travel to an education center to attend a class. Below is a selection of the events already on the schedule.

The MySQL developer tools team announces 6.2.2 RC – the final release candidate for MySQL Workbench 6.2.

MySQL Workbench 6.2 is the upcoming major update for the official MySQL 
graphical development tool .

MySQL Workbench 6.2 focuses on support for innovations released in MySQL 5.6  and MySQL 5.7
DMR (Development Release) as well as MySQL Fabric 1.5, with features such as:

• A new spatial data viewer, allowing graphical views of result sets containing GEOMETRY data and
   taking advantage of the new GIS capabilities in MySQL 5.7.
• Support for new MySQL 5.7.4 SQL syntax and configuration options.
• Metadata Locks View shows the locks connections are blocked or waiting on.
• MySQL Fabric cluster connectivity – Browsing, view status, and connect to any MySQL instance in a 
  Fabric Cluster. …

Percona is glad to announce the new release of Percona XtraDB Cluster 5.5 on September 5th 2014. Binaries are available from downloads area or from our software repositories.

Based on Percona Server 5.5.39-36.0 including all the bug fixes in it, Galera Replicator 2.11, and on …

Thank you to all of you who attended my webinar last week about Global Transaction IDs (GTIDs), which were introduced in MySQL 5.6 to make the reconfiguration of replication straightforward. If you missed my webinar, you can still listen to the recording and download the sides (free). We had a lot of questions during the webinar, so let me try to answer them here. Please let me know in the comments if additional clarification is needed.

Q: Does GTID provide any benefit to master-master replication? If yes, how?
Q: Is ACTIVE ACTIVE MASTER MASTER successful in MySQL with GTID? …

In some cases it is not possible to use an index to optimize a JOIN. This may for example happen when you query the Performance Schema. As a result these kind of queries can be very slow; however in MySQL 5.6 and later you can use a trick to improve the performance considerably.

As a working example in this post, I will use the schema_table_statistics view in the sys schema. Since the view involves the schema, I will create a reasonable large number of databases and tables for the test:

shell$ for ((i=0; i<100; i++)); do
>    echo "Database ${i}"
>    mysql -e "CREATE DATABASE db${i}"
>    for ((j=0; j<100; j++)); do
>        mysql -e "CREATE TABLE db${i}.t${j} (id int unsigned NOT NULL auto_increment PRIMARY KEY, val varchar(10) NOT NULL) …

Daniel was tracking down what appeared to be a networking problem….

• server reported 113 (No route to host)
• However, an strace did not reveal the networking stack ever returning that.
• On the other side, IP packets were actually received.
• When confronted with mysteries like this, I get suspicious – mainly of (fellow) programmers.
• I suggested a grep through the source code, which revealed  return -EHOSTUNREACH;
• Mystery solved, which allowed us to find what was actually going on.

Lessons:

1. Don’t just believe or presume the supposed origin of an error.
2. Programmers often take shortcuts that cause grief later. I fully appreciate how the above code came about, but I still think it was wrong. Mapping a “similar” situation onto an existing …

Continuent is delighted to announce an exciting Continuent Tungsten feature addition for MySQL users: replication in real-time from MySQL into Amazon RedShift.  

In this webinar-on-demand we survey Continuent Tungsten capabilities for data warehouse loading, then zero in on practical details of setting up replication from MySQL into RedShift.  We cover:

Introduction to real-time movement

Introduction 

MySQL Enterprise Backup (MEB) is a highly efficient tool for taking backups of your MySQL databases. In the 3.11.0 release, we are taking that one step further by introducing a new concept called "optimistic" backup. Optimistic backup leverages the patterns we saw frequently especially as related to very large databases.

For backups the goals are:

1 - Quality and Consistency - the backup and more importantly the restore just "works".
2 - Size, time, and overhead - like in the game of golf - low score wins - for backups and for
     restores.
3 - Flexibility – It’s not always one size fits all - whether how the backup is run, where it goes,
     how it is recovered.

With optimistic backup - we look at mostly the read aspects of your database to enable us to create a backup that is smaller, faster to backup, faster to …

I’ve just released the 1.1.0 version of the MySQL sys schema.

This release is hugely pleasing to me, in that I actually didn’t have to do too much work on it myself! There were a significant number of contributions from Jesper Wisborg Krogh and Arnaud Adant, both MySQL Support Engineers (at the time at least, Arnaud has moved on to pastures new now), as well as again from Joe Grasse.

Thank you all for your contributions!

Here’s a summary of the changes:

Improvements

• Added host summary views, which have the same structure as the user summary views, but aggregated by host instead (Contributed by Arnaud Adant)
  • host_summary
  • host_summary_by_file_io_type
  • host_summary_by_file_io
  …