It is great to draw inspiration from other Open Source communities. Brad Fitzpatrick recently wrote about Android Strict Mode. His twitter tag line for this post was “I see you were doing 120 ms in a 16 ms zone” which is all I needed to hear from somebody who also worries unreasonably about responsiveness (Web site quote).

How would I apply this to a MySQL context? This is what happens in Android. “Strict Mode lets you set a policy on a thread declaring what you’re not allowed to do on that thread, and what the penalty is if you violate the policy. Implementation-wise, this policy is simply a thread-local integer bitmask. By default everything is allowed and it won’t get in your way unless you want it to”

In a MySQL …

An update of MySQL from 5.0 to 5.5 on CentOS 5.5 64bit has not resulted in a good experience. The mysqld process would then crash every few minutes with the following message.

101120 8:29:27 InnoDB: Operating system error number 22 in a file operation.
InnoDB: Error number 22 means ‘Invalid argument’.
InnoDB: Some operating system error numbers are described at
InnoDB: http://dev.mysql.com/doc/refman/5.1/en/operating-system-error-codes.html
InnoDB: File name /tmpfs/#sql6cf3_5c_0.ibd
InnoDB: File operation call: ‘aio write’.
InnoDB: Cannot continue operation.

The work around was to change the tmpdir=/tmpfs (which was a 16G tmpfs filesystem) to a physical disk.

The referenced URL didn’t provide any more information of help. Unlike Bug #26662 O_DIRECT is not specified as the flush method.

One significant new feature of MySQL 5.5 is the Performance Schema. I recently performed an upgrade from 5.0 to 5.5, however my check of differences in the MySQL variables via mysqladmin variables failed because we now have a new record long variable name “performance_schema_events_waits_history_long_size”.

The full list of new performance_schema variables are:

> | performance_schema_events_waits_history_long_size | 10000                                                                                                                  |
> | performance_schema_events_waits_history_size      | 10                                                                                                                     |
> | performance_schema_max_cond_classes               | 80 …

So your not a MySQL DBA, but you have to perform like one. If you have a production environment that’s running now, what are the first things you do when it’s not running or reported as not running?

1. Are the MySQL processes running? (i.e. mysqld and mysqld_safe)
2. Can you connect locally via cli?
3. What’s in the MySQL error log?
4. What are current MySQL threads doing? Locked? long running? how many? idle sources?
5. Can you connect remotely via cli?
6. Verify free diskspace?
7. Verify system physical resources?
8. If this is a slave, is MySQL replication running? Is it up to date?
9. What is the current MySQL load, e.g. reads/writes/throughput/network/disk etc?
10. What is the current InnoDB state and load? (based on if your using InnoDB)

After you do this manually more then once you should be scripting these commands to …

Starting with the great work of Yoshinori-san Using MySQL as a NoSQL – A story for exceeding 750,000 qps on a commodity server and Golan Zakai who posted Installing Dena’s HandlerSocket NoSQL plugin for MySQL on Centos I configured and tested HandlerSocket under Ubuntu 10.04 64bit.

NOTE: This machine already compiles MySQL and Drizzle. You should refer to appropriate source compile instructions for necessary dependencies.

# Get Software
cd /some/path
export DIR=`pwd`
wget http://download.github.com/ahiguti-HandlerSocket-Plugin-for-MySQL-1.0.6-10-gd032ec0.tar.gz
wget http://mysql.mirror.iweb.ca/Downloads/MySQL-5.1/mysql-5.1.52.tar.gz
wget …

There are three simple practices that can improve general INSERT throughput. Each requires consideration on how the data is collected and what is acceptable data loss in a disaster.

General inserting of rows can be performed as single INSERT’s for example.

INSERT INTO table (col1, col2, col3) VALUES (?, ?, ?);
INSERT INTO table (col1, col2, col3) VALUES (?, ?, ?);
INSERT INTO table (col1, col2, col3) VALUES (?, ?, ?);

While this works, there are two scalability limitations. First is the network overhead of the back and forth of each SQL statement, the second is the synchronous nature, that is your code can not continue until your INSERT is successfully completed.

The first improvement is to use MySQL’s multi values capability with INSERT. That is you can insert multiple rows with a single INSERT statement. For example:

INSERT INTO table (col1, col2, col3) VALUES (?, ?, ?),  (?, ?, ?), (?, ?, ?);

2010 has been the first year I have re-presented any of my developed MySQL presentations. Historically I have always created new presentations, however Paul Vallee gave me some valuable advice at UC 2010. In the past two weeks I’ve traveled to seven countries in South America on the OTN LA tour where I have been speaking about and promoting MySQL.

My three current presentations have been improved and even simplified, more future improvements are planned. There is definitely a benefit in repeating a good presentation multiple times.

My SQL Idiosyncrasies That Bite OTN View more …

Oracle has released news about changing policies of MySQL Enterprise Support effectively dropping annual support for Basic and Silver. The entry level support is now $3000 per server per year. The MySQL support team now part of Oracle has great resources however Oracle is in the business of making money. When a general company question for OOW is company income, and the first option is < $50 million it highlights that startups, and smaller companies are clearly not a focus.

The success of MySQL as an open source company has lead to other leading providers that now can provide enterprise level support. More importantly many organizations over per-incident support which is more cost effect. News in the past week has included Percona - …

This is one of the MySQL presentations I’m doing on the OTN LAD Tour in South America, starting today in Lima, Peru.

MySQL Best Practices for DBAs and Developers

Learn the right techniques to maximize your investment in MySQL by knowing the best practices for DBAs and Developers. Understand what subtle differences between MySQL and other RDBMS products are essential to understand in order to maximize the benefits and strengths of MySQL. We will be covering areas including the minimum MySQL configuration, ideal SQL, MySQL security and schema optimizations.

• MySQL Configuration default settings including SQL_MODE
• Documenting, formatting and future proofing your SQL
• Developing and reviewing all SQL paths
• MySQL physical and user security
• The best schema optimizations
• Essential Monitoring and …

Announced at MySQL Sunday was the Release Candidate edition of MySQL 5.5.6. Also noted by Geert where he points out the default storage engine is now InnoDB.

However, for those from a background other then MySQL there is still a gotcha.

mysql> show global variables like 'autocommit';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| autocommit    | ON    |
+---------------+-------+

Unlike Oracle for example, the default autocommit is on.

Doing some other boundary conditions, it is no longer possible to disable InnoDB on startup which you would of course expect.

$ bin/mysqld_safe --skip-innodb &
$ tail error.log

101003 15:33:32 [Note] Plugin 'InnoDB' is disabled.
101003 15:33:32 [ERROR] Unknown/unsupported storage engine: InnoDB
101003 15:33:32 [ERROR] Aborting

MyISAM however can’t be removed …