I just wanted to express my appreciation for the 5.5 release. I know a lot of great engineers, documentation writers, testers, packagers, product managers, and even non-technical people must have done far more work on this release than we can see externally to Oracle, and many of those people might not be named anywhere. I know who some of you are, but surely not all of you. And, thanks to those who began this effort years ago at MySQL and then at Sun, who may not be involved anymore.

BackgroundNormally, I would use a comment. The first thing I would think is
CREATE PROCEDURE p1(i int) select "hello" /* This is my text */
But most client libraries will strip it.
There was a …

As we can see, MySQL 5.5.8 comes with great improvements and scalability fixes. Adding up all the new features, you have a great release. However, there is one area I want to touch on in this post. At Percona, we consider it important not only to have the best peak performance, but also stable and predictable performance. I refer you to Peter's post, Performance Optimization and Six Sigma.

In Percona Server (and actually even before that, in percona-patches builds for 5.0), we added adaptive checkpoint algorithms, and later the InnoDB-plugin included an implementation of  "adaptive flushing". This post shows the differences between them and MySQL.

The post also answers the question of whether we are going to have releases of Percona Server/XtraDB based on the …

You may have seen my posting regarding "eventual consistency" some months ago, and you may have come to the conclusion that I was insisting that a SQL based RDBMS is the way to go for just about anything. Tell you what, that is not so. And nether am I against using. say, MongoDB, where it is appropriate.

The whole deal with Eventual consistency is something that I am still opposed to, I want to know if my data is consistent. And I am not not sure that you cannot have a fully consistent, distributed system either. But I guess that debate goes on. And I still want my base data to be consistent. Like in RDBMS-SQL-Foreign-keys-all-over-the-place-and-not-a-bl**dy-bit-lost-in-the-MyISAM-swamp consistent. That is what I want the base data to look like. And if there are compromises …

We're publishing a new Strata Gem each day all the way through to December 24. Yesterday's Gem: What your inbox knows.

The trend for NoSQL stores such as memcache for fast key-value storage should give us pause for thought: what have regular database vendors been doing all this time? An important new project, HandlerSocket, seeks to leverage MySQL's raw speed for key-value storage.

NoSQL databases offer fast key-value storage for use in backing web applications, but years of work on regular relational databases has hardly ignored performance. The main performance hit with regular databases is in interpreting queries.

Last Friday I published results of DBT2 performance while varying the number of idle connections here, but I had compiled MySQL with the debugging code enabled. That completely screw up my results, be aware... debug options have a huge performance impact. So, I recompiled Percona-Server 11.2 without the debug options and did another benchmark run. The result is shown below:

As you can see, the impact is more moderate and far less shocking. The performance loss is approximately of 1% per 1000 of idle connections. Although it is something to keep in mind, there is no big stress with these idle connections.

Entry posted by Yves Trudeau | …

Hey everyone,

I always attend the O'REILLY MySQL Conference in April every year, but this year found another interesting conference that brings both Oracle and MySQL users together, KSCOPE11. This will be the second year with a dedicated MySQL track at Kscope11. There will be a clear focus on providing both developers and DBAs the right information, tools and best practices within MySQL, emphasizing scalability and performance.

I'll be presenting "MySQL HA Possibilites" at KSCOPE11 next June.

This talk will cover high availability techniques, sharding fundamentals, third party technologies, and how to decrease the likelihood of system outages

* High availability overview and terms
* Scale up …

This content has been updated and moved to a new place. As you are probably aware, PHP 5.3.4 does not compile with MySQL 5.5 GA. The details can be seen in MySQL bug queue. Basically, the problem boils down to incorrect installation of MySQL headers. MySQL 5.5 build system does not install the headers under the include-prefix/mysql directly but instead installs under the include-prefix directory itself. So, when the PHP build system looks for the MySQL headers, it cannot find …

COUNT function counts the number of rows retrieved by a SELECT statement. The return value is of type BIGINT. The COUNT(expr) function count the number of non-NULL values of expr in the rows retrieved by a SELECT statement. SELECT COUNT(expr) FROM tbl; In contrast, COUNT(*) is different in that it returns a count of the […]

There have been many posts about performance, benchmarking and the results. Many DBAs have talked in the past about the deadline scheduler, available in all modern Linux distributions.  The deadline scheduler is very effective for database systems, as it tries to prevent starvation of I/O requests.  To see what the net effect of using the deadline scheduler looks like, I am using a simple TPCC benchmark program, created by the Percona team, tpcc-mysql to measure the number of New-Order transactions per minute (TpmC).  All of the testing was performed using RedHat Enterprise Linux 5, using the standard ext3 file system and a combination of the default scheduler (cfq) and the deadline scheduler (dl):

CFQ:  845 TpmC DL:  2145 TpmC

This is a huge difference in performance between the two schedulers. …