It’s a shame that MySQL does not provide better granularity when you want to look at all SQL statements being executed in a MySQL server. I canvas that you can with the general log, but the inherit starting/stopping problems in 5.0, improved in 5.1, but I would still like to see the option on a per connection basis, or even a time period. MySQL Proxy can provide a solution here but also with some caveats.

You should however in a NON production environment, take the time to enable the general log and look the SQL Statements. Prior to looking at the SQL, monitoring of the GLOBAL STATUS variables combined with Statpack revealed the following in a 1 minute interval.

====================================================================================================
                                         Statement Activity …

This neat one line command can be of interest when you are rebuilding a MySQL slave and replication is currently catching up.

$ watch --interval=1 --differences 'mysql -uuser -ppassword -e "show slave status\G"'

You will see the standard SHOW SLAVE STATUS output, but the watch command presents an updated view every second, and highlights differences. This can be useful in a background window to keep an eye on those ‘Seconds Behind Master’.

*************************** 1. row ***************************
             Slave_IO_State: Waiting for master to send event
                Master_Host: 10.10.10.10
                Master_User: slave
                Master_Port: 3306
              Connect_Retry: 60
            Master_Log_File: mysql-bin.000626
        Read_Master_Log_Pos: 88159239
             Relay_Log_File: slave-relay.000005
              Relay_Log_Pos: 426677632
      Relay_Master_Log_File: mysql-bin.000621 …

I had the opportunity to review a client’s production Drupal installation recently. This is a new site and traffic is just starting to pick up. Drupal is a popular LAMP stack open source CMS system using the MySQL Database.

Unfortunately I don’t always have the chance to focus on one product when consulting, sometimes the time can be minutes to a few hours. Some observations from looking at Drupal.

Disk footprint

Presently, volume and content is of a low volume, but expecting to ramp up. I do however find 90% of disk volume in one table called ‘watchdog’;

+--------------+--------------+--------------+-------------+--------+
| table_schema | total_mb     | data_mb      | index_mb    | tables |
+--------------+--------------+--------------+-------------+--------+
| xxxxx        | 812.95555878 | …

MySQL by default is vary lax with data validation. Silent conversions is a concept that is not a common practice in other databases. In MySQL, instead of throwing an error, a warning was thrown and many applications simply did not handle warnings. With the introduction of sql_mode=STRICT_ALL_TABLES (or TRADITIONAL), in MySQL 5, a better level of validation now exists.

My understanding was that Warnings are now thrown as Errors, therefore eliminating the need to do a SHOW WARNINGS to confirm any problems after every query (this is a performance overhead on a high volume system due to the round trip latency).

However I found an instance where MySQL in STRICT Mode still throws warnings, leading to the question, are there any other areas, and does the earlier statement “Warnings are now thrown as Errors” hold true.

Here is my seeding process to showing the problem.

mysql> create table i(i tinyint, unique key( …

The current size of a MySQL 5.1.30 installation is around 420M.

$ du -sh .
426M    .

A further breakdown.

$ du -sh *
213M    bin
20K     COPYING
9.8M    docs
8.0K    EXCEPTIONS-CLIENT
436K    include
12K     INSTALL-BINARY
121M    lib
504K    man
4.0K    my.cnf
77M     mysql-test
4.0K    README
20K     scripts
2.3M    share
2.9M    sql-bench
100K    support-files

A means to reduce the footprint by 25% is to delete some unused stuff.

$ rm -rf docs/ mysql-test/ sql-bench/
$ du -sh .
337M    .

It’s no big deal, however it certainly does cut down on verbose output in the backup logs removing the mysql-test directory and files.

In just over 2 weeks I’ll be the invited speaker in Washington DC to Best practices for migrating applications to MySQL. This workshop is being held in conjunction with Carahsoft and Sun/MySQL and aims to provide to the Federal sector valuable information for the continued usage and uptake of Open Source and specifically MySQL.

As part of my preparation I’m happy to hear from any organizations that have successfully migrated from Oracle/SQL Server/Informix/Sybase etc to MySQL and would like to be cited.

While I have been involved in the process I am also happy to hear of reasons why a migration failed, was aborted or postponed. This is all valuable information in determining what are the most ideal applications.

Learn how to extend your existing MySQL based website to leverage the power of MySQL variants, AWS cloud based MySQL deployments and RDBMS alternatives. Evaluate how to integrate and use these different various technologies such as MySQL based variations KickFire, a column based optimization and InfoBright, a data warehousing solution. Understand the means of approach towards data synchronization between various database solutions in your business.

At the MySQL Meetup in New York this month, I spoke on “Extending the MySQL Data Landscape“. A MySQL centric view on an earlier work, “The Data Landscape” which I presented at a recent GoDaddy Tech Day.

You can download the presentation on my Presentations page.

I was doing some database sizing in MySQL 5.1.30 GA for memory tables. Generally I have used INFORMATION_SCHEMA.TABLES data_length,index_length as a reasonable guide.

However working with a MEMORY table, after deleting rows, the size did not decrease as expected. I deleted 10% of rows, and saw 0% reduction. This was confirmed by doing a subsequent ALTER where I saw the 10% reduction in memory size.

It requires more investigation, however I found these results unexpected and worthy of publishing.

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.1.30    |
+-----------+

+-----------------+--------+------------+------------+----------------+-------------+-------------+------------+
| table_name      | engine | row_format | table_rows | avg_row_length | total_mb    | data_mb     | index_mb   |
+-----------------+--------+------------+------------+----------------+-------------+-------------+------------+
| …

As discussed previously in Options using MySQL pairs I have started evaluating the strengths and weaknesses of various open source options. This is an evaluation of Flipper, a product from Proven Scaling a MySQL consulting organization.

Overall

• Pros When correctly configured and with a working installation it just works, simple and functional, which is good design.
• Cons The functionality is incomplete especially when it comes to edge cases, additional manual scripting especially for MySQL specifics is necessary and could have be easily added.

The …

My presentation from the 2008 MySQL Conference on Top 20 Design Tips for Data Architects has been receiving a lot of traffic lately.

Most recently this presentation was featured on the front page of Slideshare, as well as last month I made the top 10 of Hacker News.