MySQL 5.6 allows you to execute replicated events in parallel as long as data is split across several databases. This feature is named “Multi-Threaded Slave” (MTS) and it is easy to enable by setting slave_parallel_workers to a > 1 value. However if you decide to use MTS without GTIDs, you may run into annoying issues. Let’s look at two of them.

Skipping replication errors

When replication stops with an error, a frequent approach is to “ignore now and fix later.” This means you will run SET GLOBAL sql_slave_skip_counter=1 to be able to restart replication as quickly as possible and later use pt-table-checksum/pt-table-sync to resync data on the slave.

Then the day when I hit:

mysql> show slave status;
[...]
Last_SQL_Error: Worker 0 failed executing transaction '' at master log mysql-bin.000017, end_log_pos 1216451; Error 'Duplicate entry '1001' for key 'PRIMARY'' on query. …

Qualys announced they had found an exploit in one of the Linux core libraries – glibc – using a buffer overflow technique in gethostbyname(). They have developed a proof-of-concept in which simply sending a specially created e-mail to a mail server enabled them to create a remote shell to the Linux machine. According to Qualys, “This bypasses all existing protections (like ASLR, PIE and NX) on both 32-bit and 64-bit systems.”. How does it affect MySQL servers? Read on!

The vulnerable library call provides DNS name resolution and although it’s been obsoleted in favour of other calls, it is still widely used by both legacy and modern applications.

Having a quick search, MySQL does not seem to rely on gethostbyname() almost at all. A few uses can be found in MySQL Cluster code (NDB), …

Download MariaDB 10.0.16

Release Notes Changelog What is MariaDB 10.0?

MariaDB APT and YUM Repository Configuration Generator

The MariaDB project is pleased to announce the immediate availability of MariaDB 10.0.16. This is a Stable (GA) release.

See the Release Notes and …

Madrid MySQL Users Group will have its next meeting on Thursday, the 29th of January. I will be giving a presentation on the MySQL binlog server and how it can be used to help scale reads and be used for other purposes.  If you have (more than) a few slaves this talk might be interesting … Continue reading MMUG11: Talk about binlog servers at Madrid MySQL Users Group meeting on 29th January 2015

The post MMUG11: Talk about binlog servers at Madrid MySQL Users Group meeting on 29th January 2015 first appeared on Simon J Mudd's Blog.

 Long time ago I wrote a blog post that we started using Semi-Synchronous replication in production at Facebook. We are running our own MySQL facebook-5.6 branch, which added many replication (including Semisync) patches. Some of them were also merged with WebScaleSQL.

 Recently I heard from people from community that they were suffering from Semisync performance issues in official MySQL 5.6. I took some time to review our previous MySQL bug reports, then realized that some important bugs were either still "verified" or inefficiently fixed. Two most affecting bug reports were …

I’ll be presenting Undrop for InnoDB data recovery toolkit on Percona Live 2015. The conference takes place in Santa Clara on 13-16 April.

You may wonder why do I care if I plan to drop none of my production databases. To name few reasons:

• Taxes, death and data loss are inevitable
• Good knowledge of how InnoDB stores data on disk help to design fast and scalable databases
• The toolkit can be used to troubleshoot bugs in InnoDB.

So bookmark the session, it’s going to be a great discussion.

Undrop for InnoDB | Percona Live MySQL Conference 2015

The post Presenting Undrop for InnoDB Toolkit on Percona Live 2015 appeared first on …

January 27, 2015 By Severalnines

Unlike standard MySQL server and MySQL Cluster, the way to start a MySQL/MariaDB Galera Cluster is a bit different. Galera requires you to start a node in a cluster as a reference point, before the remaining nodes are able to join and form the cluster. This process is known as cluster bootstrap. Bootstrapping is an initial step to introduce a database node as primary component, before others see it as a reference point to sync up data.

How does it work?

When Galera starts with the bootstrap command on a node, that particular node will reach Primary state (check the value of wsrep_cluster_status). The remaining nodes will just require a normal start command and they will automatically look for existing Primary Component (PC) in the cluster and join to form a cluster. Data synchronization then happens through either incremental state transfer (IST) or …

In this blog post, we will discuss MySQL performance on eXFlash DIMMs. Earlier we measured the IO performance of these storage devices with sysbench fileio.

Environment

The benchmarking environment was the same as the one we did sysbench fileio in.

CPU: 2x Intel Xeon E5-2690 (hyper threading enabled)
FusionIO driver version: 3.2.6 build 1212
Operating system: CentOS 6.5
Kernel version: 2.6.32-431.el6.x86_64

In this case, we used a separate machine for testing which had a 10G ethernet connection to this server. This server executed sysbench. The client was not the bottleneck in this case. The environment is described in greater detail at the end of the blog post.

Sysbench OLTP write workload

…

Today is my last day at Tokutek. On Monday I'm starting a new opportunity as VP/Technology at CrunchTime!. If you are a web developer, database developer, or quality assurance engineer in the Boston area and looking for a new opportunity please contact me or visit the CrunchTime! career page.

I've really enjoyed my time at VoltDB and Tokutek. Working for Mike Stonebraker (at VoltDB) was on my career "bucket list" and in these past 3.5 years at Tokutek I've experienced the awesomeness of the MySQL ecosystem and the surging NoSQL database …

For months when speaking with customers I have been positioning Percona Cloud Tools (PCT) as a valuable tool for the DBA/Developer/SysAdmin but only recently have I truly been able to harness the data and make a technical recommendation to a customer that I feel would have been very difficult to accomplish otherwise.

Let me provide some background: I was tasked with performing a Performance Audit for one of our customers (Performance Audits are extremely popular as they allow you to have a MySQL Expert confirm or reveal challenges within your MySQL environment and make your database run faster!) and as part of our …