Look at MySQL bug reports of course? Well actually I’m writing multiple blog posts, and I was confirming additional reference sources and links when I came across MySQL Bug #29847 - Large CPU usage of InnoDB crash recovery with a big buf pool.

Taking the time to actually read the information exchange I stumble upon.

[8 Jun 23:29] liz drachnik

Hello Heikki - 

In order for us to continue the process of reviewing your contribution to MySQL - We need
you to review and sign the Sun|MySQL contributor agreement (the "SCA")

The process is explained here:
http://forge.mysql.com/wiki/Sun_Contributor_Agreement

Getting a signed/approved SCA on file will help us facilitate your contribution-- this
one, and others in the future.

Thank you ! 

Liz Drachnik  - Program Manager - MySQL

Oops. Well it made me laugh out loud for so many reasons. First your talking to the …

Recently with a client while running a number of disaster recovery tests I came across a nasty situation which was not part of the original plan and provided a far worse disaster situation then expected.

I should preface this condition with some of the environment conditions.

• MySQL 5.0 Enterprise 5.0.54
• RHEL 5 64bit
• Master and 2 Slaves
• MySQL Data and MySQL Binary Logs/MySQL Error Logs are on separate disk partitions

While running stress tests under high load, we tested the filling of partition containing the logs. This partition included the binary log and MySQL error log.

The observed output was.

• An error message was written to the MySQL error log. See below.
• Application throughput dropped, but did not stop.
• Binary logs stopped occuring.
• MySQL proactively stopped logging but continued to process …

Multi versioning concurrency control (MVCC) is a database design theory that enables relational databases to support concurrency, or more simply multiple user access to common data in your database.

In MySQL the InnoDB storage engine provides MVCC, row-level locking, full ACID compliance as well as other features.

In my understanding of database theory, access to modify independent sections of unique data (e.g. UPDATE) under MVCC should fully support concurrency. I have however experienced a level of exclusive locking under Innodb.

I wanted to clearly document this situation so I could then seek the advice of the guru’s in InnoDB Internals such as Mark Callaghan, Percona and the Innodb development team for example. I’m happy …

A couple of  weeks ago I got an unhappy email from my web hosting provider telling me I was in violation of their Terms of Service. Of course I called them immediately and was told that there was a “phishing page” hidden in one of my web directories. My blog had been hacked, so I immediately started doing some house cleaning.

After the initial once over and deletion of any suspicious files I went looking for advice on how to “harden my installation”. Here’s what I found:

• Wordpress.org Codex Hardening Wordpress - Lots of good information here on hardening Wordpress including a general overview of Wordpress security considerations.
• …

The MySQL KILL command as the name suggests kills queries that are running.

After identifying the Id using the SHOW PROCESSLIST command, the User of the connection/thread or a database user with SUPER privileges can execute KILL [id]; to remove the connection/thread.

However, there is an ability to kill just the query that is being executed rather the entire connection. The default when not specified is to kill the connection, however you can optional specify the CONNECTION or QUERY keywords.

For example, below is an interactive test.

Thread 1:

mysql> select sleep(10);

Thread 2:

mysql> show processlist;
+----+------+-----------+------+---------+------+-----------+------------------+
| Id | User | Host      | db   | Command | Time | State     | Info             | …

Today we increased price for the Amanda Enterprise Backup Server. The new price for our Standard subscription level is $500 per year. Our online store is a place to quickly checkout prices for all our products on a single page. This price increase was done in conjunction with release of Amanda Enterprise 3.0, which represents several man years of R&D on the backup server, including advanced media management such as D2D2T. Our subscription provides access to software and enterprise-class support.

Amanda Enterprise is used by businesses of all shapes and sizes. But a typical scenario is the following:

• Backup Server on Linux
• One tape library with one or two tape drives. Or VTL on a NAS device.
• A mix of Linux & Windows servers and desktops …

There are many features that are similar in MySQL and Drizzle. There are also many that are not.

I’ve previously discussed topics like Datatypes and tables, SQL_MODE and SHOW.

A key difference in Drizzle is the definition of utf8 as 4 bytes, not 3 bytes as in MySQL. This combined with no other character sets leads to an impact on the length in keys supported in Innodb.

During a recent test with a client, I was unable to successfully migrated the schema and provide the same schema due to unique indexes defined for utf8 VARHAR(255) fields.

Here is the problem. …

I was trying to demonstrate to a client how to monitor queries that generate internal temporary tables. With an EXPLAIN plan you see ‘Creating temporary’. Within MySQL you can use the SHOW STATUS to look at queries that create temporary tables.

There is the issue that the act of monitoring impacts the results, SHOW STATUS actually creates a temporary table. You can see in this example.

mysql> select version();
+-----------------+
| version()       |
+-----------------+
| 5.1.31-1ubuntu2 |
+-----------------+
1 row in set (0.00 sec)

mysql> show global status like 'created_tmp%';
+-------------------------+-------+
| Variable_name           | Value |
+-------------------------+-------+
| Created_tmp_disk_tables | 48    |
| Created_tmp_files       | 5     |
| Created_tmp_tables      | 155   |
+-------------------------+-------+
3 rows in set (0.00 sec)

mysql> show global status like 'created_tmp%';
+-------------------------+-------+
| …

With thanks to Patrick Galbraith and his DBD::drizzle 0.200 I am now able to test client benchmarks side by side with MySQL and Drizzle.

For simple benchmarking with clients, generally when I have little time, I use a simple Perl framework mybench. I was able to change just the connection string and run tests.

The diff of my two scripts where:

---
> my $user      = $opt{u} || "appuser";
> my $pass      = $opt{p} || "password";
> my $port      = $opt{P} || 3306;
> my $dsn       = "DBI:mysql:$db:$host;port=$port";
---
< my $user      = $opt{u} || "root";
< my $pass      = $opt{p} || "";
< my $port      = $opt{P} || 4427;
< my $dsn       = "DBI:drizzle:$db:$host;port=$port";
---

It’s too early to tell what improvement Drizzle will make. Just running my …

Following up on yesterday's post about Peter Drucker's principles of effective executives, I asked former CEO of MySQL Mårten Mickos to discuss the principles that we has used in building an effective executive team. After all no single executive can be successful on their own; to build a high-performance culture requires a discipline that extends across the entire leadership.

read more