If you’ve ever looked at the COM_XYZ status counters in MySQL’s SHOW STATUS output, you’ve probably seen Com_admin_commands. It’s not clear what this means, but it can be a major contributor to overall COM_ counters, and it’s actually quite important for server and application performance, as well as being a marker of code quality. In this blog post I’ll explain what the counter really means, and then as a bonus I’ll demonstrate that VividCortex will show you exactly what’s going on in the murkiness of “admin commands.”

What Does The Com_admin_commands Counter Mean?

The first question is “what is this counter?” The manual isn’t really helpful. It just says the following:

The Com_xxx statement counter variables …

Introduction

Causal consistency [1] is one of the consistency criteria that can be used on distributed databases as consistency criteria.

Distributed database provides causal consistency if read and write operations that are causally related are seen by every node of the distributed system in the same order. Concurrent writes may be seen in different order in diffrent nodes.  Causal consistency is waker than sequential consistency [2] but stronger than eventual consistency [3]. See earlier blog for more detailed description on eventual consistency https://blog.mariadb.org/eventually-consistent-databases-state-of-the-art/.

When a transaction performs a read operation followed later by a write operation, even on different object, the first read is said to be causally ordered before the write. This is because the …

Earlier this week, I presented a webinar on MySQL High Availability options for MySQL – what they are and how to choose the most appropriate one for your application.

The replay of this webinar can now be viewed here or if you just want to look at the charts then scroll down. At the end of this post, I include a summary of the Q&A from the webinar.

How important is your data? Can you afford to lose it? What about just some of it? What would be the impact if you couldn’t access it for a minute, an hour, a day or a week?

Different applications can have very different requirements for High Availability. Some need 100% …

MySQL 5.7 has had some great improvements within Performance Schema to be able to better trace what connections are doing, from adding memory information, through to transaction information, metadata locking, prepared statements, and even user variables, so far (there is still more to come in the next release – stay tuned).

Of course there are other improvements on top of this as well, such as the …

Thanks to everyone who attended and participated in last week’s webinar on ‘A DevOps Guide to Database Infrastructure Automation for eCommerce’. If you missed the sessions or would like to watch the webinar again & browse through the slides, they are now available online.

Our guest speaker this time was Riaan Nolan of Foodpanda/Rocket Internet. Topics included a roundup of infrastructure challenges faced by online retailers: multi-datacenter/cloud environments, configuration management, health and performance monitoring, capacity analysis and planning, elastic scaling, and automatic failure handling. Thanks again to Riaan for taking the time to speak to us!

The full agenda included: 

• eCommerce infrastructure challenges in 2014, including a sample workflow chart outlining: 
• Puppet, GitHub, Capistrano, Nginx, PHP5-FPM / Ruby, Percona XtraDB, Couchbase, SOLR, GlusterFS
…

I visited a customer some weeks back and saw some regression problem during an upgrade to MySQL 5.6. Problem was during initial setup of database, the CREATE TABLE statements was running much slower on MySQL 5.6 compared to MySQL 5.5.

I created a simple test case where I create one SQL file containing 1000 CREATE TABLE using the following statement syntax: CREATE TABLE TNNNN (i int, name VARCHAR(12))ENGINE=InnoDB;

Tested MySQL Versions:

• MySQL 5.5.42
• MySQL 5.6.22

OS: Ubuntu 14.04
HW: My Toshiba Portege laptop with 2 cores and SSD disk

MySQL 5.5.42 (Default settings)
Lets first get our baseline by running 10 runs: mysql test < /tmp/1000tables
Result: average execution time is 7.5 seconds

MySQL 5.6.22 (Default settings)
Lets first get our baseline by running 10 runs: mysql …

Coderhsip is pleased to announce a new release of Galera Cluster for MySQL consisting of MySQL-wsrep 5.6.21 and Galera 3.9, wsrep API version 25.

This release incorporates all changes up to MySQL 5.6.21 and numerous fixes  and enhancements specific to Galera replication.

Galera Cluster is now available as targeted packages and package repositories for a number of Linux distributions, including Ubuntu, Debian, Fedora, CentOS, OpenSUSE and SLES. Obtaining packages using a package repository removes the need to download individual files and facilitates the deployment and upgrade of Galera nodes.

This and future releases will be available from http://www.galeracluster.com, while previous releases remain available on LaunchPad. The source repositories and bug tracking are now on http://www.github.com/codership .

RELEASE NOTES

…

This past week was marked by a series of personal findings related to the use of Global Transaction IDs (GTIDs) on Galera-based clusters such as Percona XtraDB Cluster (PXC). The main one being the fact that transactions touching MyISAM tables (and FLUSH PRIVILEGES!) issued on a giving node of the cluster are recorded on a GTID set bearing the node’s server_uuid as “source id” and added to the binary log (if the node has binlog enabled), thus being replicated to any async replicas connected to it. However, they won’t be replicated across the cluster (that is, all of this is by design, if wsrep_replicate_myisam is …

Hej alla SMUG:are!

Nu är det återigen dags för en ny träff, och detta är ju lagom i tiden för att prata lite om kommande 5.7-releasen.
Vi kommer att bjudas på två presentationer denna gången, en som hålls av Mattias Jonsson, utvecklare i InnoDB teamet, om partionering i 5.7. Här finns det många nyheter, ni kan kolla lite på server teamets blog, http://mysqlserverteam.com/category/partitioning/
Den andra presentationen hålls av Martin Hansson, utvecklare i MySQL server teamet. Ämnet är den nya kostnadsmodellen för planering av frågor i MySQL 5.7, detta är också en stor ändring som kommer i 5.7. Läs lite mer här: http://mysqlserverteam.com/optimizer-cost-model-improvements-in-mysql-5-7-5-dmr/

Denna gången är det King som bjuder på lokaler och lite käk, så om ni går runt med candy crush på telefonen så känns det säkert som hemma!, så stort tack till King!

…

VMware Continuent, a multi-site, multi-master database cluster solution, provides a full data management solution that is already handling billions of transactions daily for our customers, on-premises and in the cloud. Join us to learn how Continuent and MySQL can run business-critical applications in vCloud Air, VMware's hybrid cloud solution. 

In this new webinar-on-demand, you will learn