Today I spent several hours trying to find a problem in our application until I found out there was a problem on the MySQL side. In our setup we have several slave machines that replicate data from a master server. The slaves are configured with a series of replicate-do-table directives in the my.cnf file so that only parts of the schema get replicated. The remaining tables are modified locally, so to avoid conflicts they are not updated with data coming from the master.

We do however have the need to replicate data from the master for some special-case tables. To solve this we usually have a column that indicates whether a record was created on a master or a slave machine and use an appropriate WHERE clause in all updates. This avoids collisions in concurrent INSERTs on the master and the slave. The application knows which of the two records to use.

Due to historical reasons I …

If you’re a frequent reader, you might have noticed that I’m on a roll contributing MySQL patches by now… there are many more to come. This is part of the reason that I founded Proven Scaling — to be able to spend my time solving interesting problems and making MySQL better. So what about triggers, stored procedures, and call stacks?

I’ve written a patch that implements three new functions in MySQL 5.01:

• CALLER(level) — Returns the SQL statement in the call stack at level, where 0 is the level containing the call to CALLER() itself (which is nearly useless), and 1 and above are any stored procedure or trigger calls that got us here.
• CALLER_DEPTH() — Returns the current depth of the call stack, not counting 0. …

I've made more improvements to the duplicate index checker. I addressed a MySQL bug Roland Bouman mentioned to me, added more tests to the suite, and made changes so it considers more types of indexes now (HASH, BTREE, SPATIAL). I made no changes to the foreign key checking.

At the recent EuroOSCON 2006 conference in Brussels, I was both a keynoter and a session speaker. I have meanwhile uploaded my presentation slides for my keynote, New Innovation Models, Policy-Making and Lobbying, and for my additional speech, EU Software Patents Reloaded, to this Web site (as PDF files).

Unfortunately, there was some confusion on the part of the organizers, due to which I only had my slides available for the keynote but not for the session on software patents. The organizers had to admit later that I had provided …

Some vulnerabilities have been reported in OpenSSL, which can be exploited by malicious people to cause a DoS (Denial of Service) and compromise a vulnerable system. To fix this problem we released an upgrade package for the Linux version of XAMPP.

This upgrade is primary for those people who a using XAMPP in a public or semi public environment, like a local network or the Internet.

You can get the upgrade from the usual place (there you also find an explanation how to install the upgrade). More information about the vulnerability: here

Taking into account 4.1 tree is still popular and is used on many production servers we
decided to make backport of patch to slow-log queries. The patch allows to specify time of slow queries in microseconds and is very helpful in a fight with problematic queries. 4.1 Patch is available here (The original patch was developed by Georg Richter georg at php net)

Dolphin SCI

Cybersite Consulting is pleased to announce that they are a reseller partner for Dolphin Internconnect Inc. hardware in Australia. The Dolphin product which implements the international SCI standard for fast speed connections offers our clients a range of benefits to suit cluster and high-availability setups.

The Dolphin SCI connections have been used throughout Europe in setting up MySQL clusters for markets such as telecoms, communications and statistical analysis. The products work well in a Linux setup and implement a specialised software connection method that bypasses the tcp/ip stack. This allows for faster access to data across the machines by reducing latency by more than 50 percent.

If you are interested in finding out more about this technology and what it c

read more

Dolphin SCI

Cybersite Consulting is pleased to announce that they are a reseller partner for Dolphin Internconnect Inc. hardware in Australia. The Dolphin product which implements the international SCI standard for fast speed connections offers our clients a range of benefits to suit cluster and high-availability setups.

The Dolphin SCI connections have been used throughout Europe in setting up MySQL clusters for markets such as telecoms, communications and statistical analysis. The products work well in a Linux setup and implement a specialised software connection method that bypasses the tcp/ip stack. This allows for faster access to data across the machines by reducing latency by more than 50 percent.

If you are interested in finding out more about this technology and what it c

read more

The obvious follow-up post to the Guide to Incompatibilities when Upgrading MySQL to Version 4.1
is a look at the incompatibilities when moving to version 5.0.

Again, I emphasize the importance of being educated about how upgrading MySQL may affect your application. These are the obvious, flagged items, but I recommend reading all of the 5.0 release notes.

Here are the items from the MySQL 5.0 release notes that are marked Warning: Incompatible change:

• 
  

• C API change: mysql_shutdown() now requires a second argument. This is a source-level incompatibility that affects how you compile client programs; it does not affect the …