Today’s post features an interview with Morgan Tocker, MySQL community manager at Oracle. Morgan is an old friend of Percona, having worked here as director of MySQL training from 2009 to 2011. He’s also done stints at MySQL, Sun Microsystems and InPowered. You can follow his adventures at his blog, “Master MySQL.”  You can also connect with him face-to-face at the Percona Live MySQL Conference and Expo this April 1-4 in Santa Clara, Calif.  Use the promotional code “SeeMeSpeak” on the registration page and save 10 percent.

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February 18, 2014 By Severalnines

Virtual Machines are great, and very useful when trying out new software. However, they might be an unnecessarily heavyweight solution when testing clusters, especially if these consist of multiple nodes running exactly the same software. Each VM runs a full-blown OS image. On the other hand, Linux Containers (LXC) are an efficient alternative to OS-level virtualization and can run multiple isolated systems on a single host. Docker is a wrapper around LXC, it automates the deployment of applications inside containers. 

A notable advantage if you run with Docker + LXC is you can run many containers on a single host. They all share the same OS as the host, and when possible, the same binaries. Deployment can be extremely fast. Using Docker could be a good method if you want to spin multiple Galera nodes within a single host. 

In this post, we will create MySQL Galera Cluster …

Over the last few years there has been an increasing interest in immutable data management. This is a big change from the traditional update-in-place approach many database systems use today, where new values delete old values, which are then lost. With immutable data you record everything, generally using methods that append data from successive transactions rather than replacing them.  In some DBMS types you can access the older values, while in others the system transparently uses the old values to solve useful problems like implementing eventual consistency.

Baron Schwartz recently pointed out that it can be hard to get decent transaction processing performance based on append-only methods like append-only B-trees.  This is not a very strong argument against immutable data per se. …

Yesterday I’ve put some new features into the ansible’s mysql_replication module, because we are planning to move to GTID based replication from the good old binlog position based one, and the module wasn’t aware of.

gtid_replication

This parameter can be either 0 or 1, defaults to 0. If set to 1 the replication will be threaded as GTID based replication.

warnings_filtered

This parameter threats the warnings, because MySQL 5.6 complaints a lot more than the previous versions. (For example, if the replication is not encrypted with SSL/TLS.) This could break our playbooks, so you can set it to all, warnings, none (defaults none). Speaks for itself, all means all warnings/errors will be shown, if warnings set, then only the errors will be shown, and the warnings supressed, and if none then that means, every message will be show …

MySQL Connectors provide connectivity to the MySQL server for client programs. APIs provide low-level access to the MySQL protocol and MySQL resources. Both Connectors and the APIs enable you to connect and execute MySQL statements from another language or environment. Oracle provides a number of these, enabling developers to build database applications in the language of their choice. Among those developed by Oracle are drivers for JDBC and ODBC. Any system that works with JDBC or ODBC can use MySQL. And you can find many more, including drivers for PHP, Perl, Python, Ruby, Tcl and even Eiffel!

To get a head start on developing with MySQL, take the MySQL for Developers training course. This …

We recently announced Percona ClusterControl supplied in partnership with Severalnines. This enterprise-grade cluster management and monitoring software is available with a Percona Support contract covering Percona XtraDB Cluster, MySQL Cluster, or MySQL Galera. In this blog post I am going to show you how to use Percona ClusterControl to to create a new 3-node cluster with Percona XtraDB Cluster.

Percona ClusterControl architecture

The software has three main parts:

• Percona ClusterControl UI: This is the web interface from where we can create new clusters and monitor and manage …

As I review with my students, a stored function works like a standalone program, while a stored procedure runs in the scope of another program unit. For example, you can compare the result of a function as an expression in an IF statement, like:

  IF add_numbers(1,3) > 3 THEN
    ...
  ELSE
    ...
  END IF;

You can’t call procedures inside an IF statement, but you can call the procedure and use a single OUT-mode (pass-by-reference) parameter from the procedure in a subsequent IF statement. You can implement a a wait procedure like that with the following example.

The example first creates two tables, the road_runner and coyote tables:

-- Drop road_runner table if exists.
DROP TABLE IF EXISTS road_runner;
 
-- Create roadrunner table.
CREATE …

MySQL has unfortunate rules for dates with two-digit years, for the date range, for post-decimal digits, for timestamp defaults ... But other DBMSs can be equally bizarre

Two-digit years

Start with two-digit years. Summarizing from the manual:

If the two-digit value is <= 69, add 2000. Else add 1900.
For example, if it's 65, then it's 2065.

It's an arbitrary extra detail that users have to learn. But PostgreSQL has exactly the same rule. And three other DBMSs -- DB2, …

This week I’ve been writing based on my linux.conf.au 2014 talk, which you can watch the recording of. Also see Part 1, Part 2, Part 3, Part 4 and Part 5. My feed feel off Planet MySQL …

I’m frequently tracking semaphores waits, and if you’ve examined them before, it can be a little matching up the threads listed in the SEMAPHORES section with the transactions in the TRANSACTIONS section.

Semaphore waits are related to internal synchronization between threads in mysqld, and not directly to row locks or other items associated with user queries, so that’s why the SEMAPHORES section only reports the OS thread id.

Fortunately, the TRANSACTIONS sections also reports the OS thread handle, but in hex format.

Here is an example semaphore wait:

--Thread 1079654736 has waited at ibuf0ibuf.c line 3549
for 943.00 seconds the semaphore:
X-lock (wait_ex) on RW-latch at 0x7f2a48830bf8 '&block->lock'
a writer (thread id 1079654736) has reserved it in mode wait exclusive
number of readers 1, waiters flag 1, lock_word: ffffffffffffffff
Last time read locked in file buf0flu.c line 1318

So how do …