I finished implementing the missing optional REGEXP function parameters today, all regular expression functions should now work as similar to their Oracle counterparts as possible with the following restrictions:

* The MySQL UDF API predates the extended character set support added with MySQL 4.1 and so UDF functions have no idea about charsets and collations at all. As a consequence the functions for now are always case sensitve by default and are always assuming their input to be Latin1 encoded
* Only the 'c' and 'i' pattern modifiers for case sensitive and insensitive matching are implemented yet, the 'm' and 'n' modifiers for multi line input are not yet supported
* I haven't tested back references on REGEXP_REPLACE() yet. They may or may not work, as i borrowed the actual implementation from the PHP source i'm not really sure about whether it takes care of this or not

Anyway, the REGEXP UDFs are hosted on …

Hi. I am doing a select like this in MySQL 5:

select * from foo where bar rlike '(.*),(.*)';

The specific example here is made up. Anyway, I'd like to be able to get to the matched text from bar, like I can with various languages regexp libraries. Is this functionality exposed at all in MySQL? I've looked at the docs and can't see any indication that it is, so this might just be wishful thinking.

Tags for this post: mysql regexp rlike select
Related posts: Managing MySQL …

A few people have asked me how fast MySQL Table Checksum is. As with so many other things, it depends. This article shows how long it takes to checksum real data on a production server I help manage, which might give you a rough idea of how long it'll take on your servers.

OSDC is a grass-roots conference providing Open Source developers with an opportunity to meet, share, learn, and of course show-off. OSDC focuses on Open Source developers building solutions directly for customers and other end users, anything goes as long as the code or the development platform is Open Source. Last year's conference attracted over 180 people, 60 talks, and 6 tutorials. Entry for delegates is kept easy by maintaining a low registration fee (approx $300), which always includes the conference dinner.

This year OSDC will be held in Brisbane from the 26th to the 29th of November, with an extra dedicated stream for presentations on Open Source business development, case studies, software process, and project management. The theme for this year's conference is "Success in Development & Business". If you are an Open Source maintainer, developer or user we would encourage you to submit a talk proposal on the open-source tools, …

Maybe this is obvious, but I post it anyway, just to remind myself should I need it again.

Recently I had to change a table that I had not completely thought through when I first created it. The structure was so simple, I did not think I could do anything wrong with it:

CREATE TABLE `parent` (
  `par_id` bigint(20) NOT NULL,
  `somevalue` varchar(20) default NULL,
  PRIMARY KEY  (`par_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `child` (
  `x_parid` bigint(20) default NULL,
  `value` bigint(10) default NULL,
  KEY `fk_parid` (`x_parid`),
  CONSTRAINT `child_ibfk_1` FOREIGN KEY (`x_parid`) REFERENCES `parent` (`par_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

There is a 1:0..* relationship between parent and child. Some sample data:

mysql> select * from parent;
+--------+--------------+
| par_id | somevalue    |
+--------+--------------+
|      1 | Parent No. 1 | 
|      2 | Parent No. 2 | 
|      3 | Parent …

Maybe this is obvious, but I post it anyway, just to remind myself should I need it again.

Recently I had to change a table that I had not completely thought through when I first created it. The structure was so simple, I did not think I could do anything wrong with it:

CREATE TABLE `parent` (
  `par_id` bigint(20) NOT NULL,
  `somevalue` varchar(20) default NULL,
  PRIMARY KEY  (`par_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `child` (
  `x_parid` bigint(20) default NULL,
  `value` bigint(10) default NULL,
  KEY `fk_parid` (`x_parid`),
  CONSTRAINT `child_ibfk_1` FOREIGN KEY (`x_parid`) REFERENCES `parent` (`par_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

There is a 1:0..* relationship between parent and child. Some sample data:

mysql> select * from parent;
+--------+--------------+
| par_id | somevalue    |
+--------+--------------+
|      1 | Parent No. 1 | 
|      2 | Parent No. 2 | 
|      3 | Parent …

Note: this "script" is a one liner really and not something meant for general purpose use. It is very specific to my environment so I take no responsibility of any kind. It is very raw so use at YOUR OWN risk.

Last year at the MySQL camp, I heard about Paul Tuckfield's script that pre-fetches relay logs to speed up replication. Since then I got really interested in implementing it but never got the time. This year at MySQL conference Paul's script got a lot of attention again. Since it hasn't been released and I really need to start testing this on my test server. So I started hacking on creating a shell script to dig deeper into what's involved. Once I have that I may work on porting it to other languages.

To make the process of writing this script easier for others in their favorite languages I thought I will go through what's involved in creating this script on my blog. That way when you would like to write an …

I've written before about how to make MySQL replication reliable. One thing I think you need to do to make statement-based replication reliable is eliminate temporary tables. I found an elegant way to replace temporary tables with real tables in the systems I maintain. This article explains how.

A few people have asked me how fast MySQL Table Checksum is. As with so many other things, it depends. This article shows how long it takes to checksum real data on a production server I help manage, which might give you a rough idea of how long it’ll take on your servers. The server and workload This server is a replication master running MySQL 5.0.38. It is a Dell Poweredge 1800 series with dual Xeon 3.

By Tim O'Reilly

In today's article about new open source releases from Sun, Microsoft, and Adobe, Wired News quoted our very own Nat Torkington:

"Microsoft is in a new era. The Bill Gates cutthroat 'we win by killing' days are passing," says Nat Torkington, co-chair of the O'Reilly Open Source Convention. "Microsoft exists by making users happy. And sometimes -- just sometimes -- you make Microsoft users happy by giving them a technology that wasn't invented at Microsoft."

Nat sure is quotable (and you should definitely read the full text of his comments), but I'm not sure that he's entirely right, at least not about the industry as a whole. Yes, in an era of open standards and open source software, it's easier for users to …