Brian Aker recently published good write up about using MySQL replication. The piece I find missing however is good description of warning about limits of this approach as well as things you need to watch out for. You can call me person with negative mind but I tend to think about limits as well. So what would be my list of limits and watch outs in this case ?

- Limited write scaling. As Brian writes this works best for read intensive envinronments. Write scaling however can be real problem. Not moderate increase of write ratio can dramatically reduce performance but you also need to watch out for slave being able to keep up at all. Remember writes to slave are serialized so if you master happens to be 8 core system with 20 hard drives you may be in trouble even if writes only consume 10% of resources as almost only one core and only one disk will be …

Igor is doing great work on moving forward the XML based database schema format originally developed by Manuel Lemos as part of Metabase that is used in MDB2_Schema. The idea is to add the ability to also handle UPDATE and DELETE statement next to the currently supported CREATE, DROP, ALTER and INSERT statements. This format is even supported by DBDesigner4 and the DatabaseSchema ez component. For the uninitiated if you: The idea behind this schema format is to make it possible to define a single database schema that can be used to create, alter and initialize databases in any number of RDBMS. For example currently MDB2_Schema supports MySQL, PostGreSQL, Oracle, SQLite, MS SQL Server, Interbase/Firebird.

While Igor and I were discussing things we discovered that we …

If there is a common method of scaling with MySQL databases it is the
Read Replication Cluster solution.

Most websites start out with a single database and grow from there.
If the site's content is being generated from their database then
they will eventually hit a wall with reads from the database. Tuning
and hardware will buy you some growth but in the end disks spin only
so quickly. Luckily most websites are predominantly read intensive
and for this reason replication will solve scaling problems for many
people. Replication is a means by which MySQL sends updates of one
database to one or more databases which will act as a slave. These
changes are atomic, which means the changes are applied in full. No
row will ever be partially updated, and no transaction will be seen
on the slave that did not commit on the master

Make a change in the …

It is always nice to be able to say a system "performs well", is very "reliable" or is "scalable". But what do these terms actually mean?

One of the primary goals of my research on SQLbusRT is finding formulas which can predict the performance, reliability and scalability of the system under development, looking at the scenario it is implemented in.

Ofcourse saying "good performance", "very reliable" and "yes it is scalable" does not suffice. The formulas should provide a meaningful outcome, which is comparable to other outcomes.

I might not be clear to everyone. Let me give an example, using something we always like to talk about: the weather.

We can say the weather is good or bad today, but that is just a personal opinion. If we want to compare todays weather with the weather of tomorrow for instance, we need numbers. We can give useful information on the weather by giving:

I've never been all that interested in solving small problems. Small problems with scaling are resolved with single indexes, upgrades to hardware, or simply creating a bigger pipe.

When the measure of the Internet was a T-1, you could flood the network with the average 486. At the time I watched people buy hardware in the hundred's of thousands, and sometimes more, which never went used. Today's hardware is overkill for a lot of applications, so the first step in scaling is often tuning the hardware that you have already purchased. Make use of what you already have.

The "Slashdot Effect" is a perfect example of what is normally a small problem. What is the Slashdot Effect? Point tens of thousands of eyeballs at a website and watch it crash. The root cause of this? Most of the time it is because the site operator had their Apache max connections set to some ridiculous number. Users would bring the site down because there …

You may have noticed the new link on dev.mysql.com to the MySQL GUI Tool Download.

This bundle includes new beta versions for MySQL Administrator, MySQL QueryBrowser, the MySQL MigrationToolkit and a new alpha version of MySQL Workbench. All these GUI products are supposed to be offered in one single package in the future.

To get all details, read Mike Zinner's Announcements in the forum:

http://forums.mysql.com/read.php?108,100559,100559#msg-100559
http://forums.mysql.com/read.php?108,100561,100561#msg-100561

Needless to say, Feedback and Bug Reports are very …

Sometime last night the crawler computed the keywords from last week. Same goal for stats as last week, take 250K of non-spam URLs for RSS and pull the contents for the week. Very error prone for aggregation sites, but ok for people who don't post enough to scroll their RSS feed. I am starting to factor out the aggregation sites and just pin point articles written by original authors.

The results:

Word: Linux: 4870
Word: PHP: 1971
Word: MySQL: 1099
Word: Perl: 992
Word: Apache: 940
Word: Ruby: 852
Word: APR: 800
Word: Python: 790
Word: Asterisk: 111

I have page refreshing results that I look at while the parsers are running. Python and Ruby play a game for a while of "who is first for the moment", with Ruby winning in the end. I am going to extend out the stats to flatten any cases of people "over using" any term, and I have some weighting …

SciBit has released update MyCon MySQL GUI v2.10 today. This is primarily a bugfix and existing feature enhancement update for v2.9.x. In short, it contains all the fixes which SciBit could already release without having our customers wait for the upcoming MyCon version 3.0 release:

* Add: Alt+C combination on any grid cell to NULL the column value of the record.
* Fix: Column Editing for MySQL >5.0.15.
* Fix: Queries now prompt before overwriting existing SQL queries

For more info on improvements made in earlier versions, see
v2.8.1
v2.8
…

I'm visiting with some of my young nieces and nephews today.  They're between the ages of 9 and 12 and they are all Habbo Hotel power users.  (Their parents thought it was "Hobbit Hotel" so I guess they are not power users!)  If you don't have young kids or nieces and nephews, you may not know it, but Habbo Hotel is virtual meeting place and game environment for teens.  They can buy, sell and trade furniture to create rooms in their hotel.  It's run by Sulake Corporation of Finland which is one of Europe's fastest growing technology companies.

Habbo Hotel runs on a LAMP stack using MySQL 5.0 with databases that range from hundreds of Gigabytes to Terabytes in size using a mixture of transactional  and non-transactional storage engines. They achieve performance levels of tens of thousands of events per second scaling out with dozens of multi-CPU …

All -

Just a quick note to let you know that a new beta release is available for all MySQL management tools (Query Browser, Administrator, Migration Toolkit, and Workbench, which is still alpha). You can download the new tools, which sport a single installer now for the entire management tools pack, here.

One great note of interest - for those wishing to migrate from Sybase to MySQL, the Migration Toolkit now has native support for moving between Sybase and MySQL! I tested it this morning and it works like a champ. Versions of Sybase supported are 12.x and higher. Those using 11.9.2 may be OK as well.

Let me know what you think!