The latest from the MySQL community

(Note : This an Article from last year when MySQL5.6 was released)

While Database technology is one of the oldest branches of computer science, it remains a fundamental computer technology that continues to attract new research. The current focus of Databases technology is towards adapting hot new tends like multi-core chips, solid state devices, NOSQL and Cloud. So what does a contemporary internet developer look for in a database for the internet era? And why does MySQL remain the most popular database for the web?

For a database to be useful while developing products for the Web, the most important requirements are that it should be quick and easy to download, quick to set up, powerful enough to get the job done, be fast and flexible to use and finally be scalable on the newest hardware. Compatibility with the latest technologies like the cloud also remains foremost in the minds of …

At MySQL, replication usability is of utmost importance to us. Replication information has long been part of SHOW commands, SHOW SLAVE STATUS occupying a major chunk of it. The other sources of replication information being:

SHOW MASTER STATUS,
SHOW BINLOG EVENTS,
SHOW RELAYLOG EVENTS,
SHOW VARIABLES,
SHOW STATUS,
…

Multi-source replication for MySQL has been released as a part of 5.7.5-labs-preview
downloadable from labs.mysql.com. It is one among the several features that are
cooking in the replication technologies at MySQL.  (For a birds eye view of all
replication features introduced in 5.7 and labs, look  at the blog posts here and here.

Previously, we have introduced a preliminary multi-source feature labs preview. Based on the feed back from that labs release, we …

Below is the excerpt from MySQL manuals on slow query log :

“By default, administrative statements are not logged, nor are queries that do not use indexes for lookups. This behavior can be changed using log_slow_admin_statements and log_queries_not_using_indexes, as described later. “

This manual entry is kind of misleading . It means that queries not using indexes are not logged by default. Let us see what the reality is :

1) Let us see if queries not using indexes are being logged.

Below table does not have index:

mysql> describe employee ;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| ID    | int(11) | YES  |     | NULL    |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> show indexes from employee ;
Empty set (0.00 sec) …

This year’s MySQL Central at Oracle Open World was an exhilarating experience. In contrast to the previous year’s MySQL Connect events, MySQL have now got their own Central at the main Oracle Open World. In the previous years, we were always short on time and trying to get a lot of sessions into just two days was just to much. This time I could both present sessions, attend sessions by other users, and also to talk to people in the MySQL community: something that I really enjoy and also find very valuable to see where we should be heading.

This year, the “MySQL Fabric Team” representation on MySQL Central was me and Narayanan Venkateswaran, which is heading the sharding solution in MySQL Fabric. Together with the conference, we also released MySQL Fabric 1.5.2 as the GA release of MySQL Fabric 1.5 containing a few new features:

• Server …

In my last post, I learned in disappointing fashion that sometimes you need to start small and work your way up, rather than trying to put together a finished product. This go-round, I’ll talk about my investigation into disk IO.

In an effort to better understand the hardware I have and it’s capacities, I started off by just trying to get some basic info about the RAID controller and the disks. This hardware in particular is a Supermicro, with a yet unknown RAID controller and 16 4TB disks arranged in RAID 6. Finding out more disk and controller information was the first step. “hdparm -i” wasn’t able to give me much, nor was “cat /sys/class/block/sdb/device/{model,vendor}”. “dmesg” …

As many learning experiences do, this one also starts out “So I was working on a project at work and…”.  In this case, the end result is to try to run as many concurrent copies of MySQL on a single server as possible, maintaining real time replication each running differing data sets. To help with this, I sent out to do this on a server with 36 7200rpm 4GB SATA disks, giving me roughly 120TB of available space to work with.

This isn’t an abnormal type of machine for us. Sometimes you simply need a ton of disk space. There is a quirk with this particular machine that I’ve been told: the RAID controller has some issues with addressing very large virtual disks and I should create 2 60TB volumes and stitch them together with LVM. Easy enough: pvcreate both volumes, create a volume group and a logical volume out of it and viola: …

The multi master plugin for MySQL is here. MySQL Group Replication provides virtually synchronous updates on any node in a group of MySQL servers, with conflict handling and automatic group membership management and failure detection.

For a better understanding on how things work, we go under the hood in this post and will analyse the transaction life cycle on multi master and which components does it interact with. But before that we need to understand first what a group is.

Group Communication Toolkit

The multi master plugin is powered by a group communication toolkit. This is what decides which servers belong to the group, performs failure detection and orders server messages. Being the ordered messaging the magic thing that allows the data to be consistent across all nodes. You can check the details of the group communication toolkit at …

More MySQL releases than ever before. Check out the following that we just released:

– MySQL Connector Java 5.1.33 GA
– MySQL Fabric & MySQL Utilities 1.5.2 GA
– MySQL Connector Python 2.0.1 GA
– MySQL Fabric and Utilities 1.6.0 Alpha
– MySQL Connector C (Labs)
– MySQL Connector Python (Labs)
– MySQL Group Replication (Labs)
– MySQL HTTP Plugin (Labs)

Download from http://dev.mysql.com/downloads/ and http://dev.mysql.com/downloads/

The multi master plugin for MySQL is here “MySQL Group Replication“. It is a virtual synchronous solution for MySQL with conflict detection. It also supports automatic group membership management, failure detection and automatic distributed recovery.

With the introduction of this new feature there was a need to perform some good amount of testing as it involves complex functionalities like :

• Servers execute local transactions and broadcasts the update to the group.
• All servers in the group, even the sender, receive same transaction in the same order and check for conflicts.
• All servers, independently, decide to commit the transaction – no conflicts.
• A new node can join an existing group, so in this case we need distributed recovery to bring it at par with the other servers.

So a great deal of effort has been spent on testing these …