There's a very useful aggregate function in mysql that allows you to concatenate several row values into one single row value. Here is an example:



mysql> create table t1 (
-> t1_id numeric,
-> col2 varchar(50)
-> );
Query OK, 0 rows affected (0.18 sec)

mysql> create table t2 (
-> t2_id numeric,
-> t1_id numeric,
-> col2 varchar(50)
-> );
Query OK, 0 rows affected (0.17 sec)

mysql> insert into t1 values (1,'a'),(2,'b'),(3,'c');
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0

mysql> insert into t2 values (1,1,'d'),(2,1,'f'),(3,2,'g'),(4,3,'f'),(5,3,'h'),(6,3,'i'),(7,3,'j');
Query OK, 7 rows affected (0.01 sec)
Records: 7 Duplicates: 0 Warnings: 0

mysql> select * from t1;
+-------+------+
| …

This blog turned 1 year old last month and I think all of my readers were glad to read it. I’ve never asked for help and I offered help to people who needed it. But today I’m forced to ask my readers for help because it is the first time in my long practice when I really don’t know how to solve my problem.

(more…)

In my previous entry I wrote how to fix Wordpress so it can avoid a possible too restrictive default SQL_MODE. I guess I should have realized that the following two lines from my my.cnf option file would probably not be liked by Wordpress either:

default-storage-engine=InnoDB              #Set the default storage engine (table type) for tables. 
init-connect="set autocommit=0"            #set autocommit off on connect

So, I went back and hacked wp-includes/wp-db.php again. Now the fix read:

// …

One of the coolest mashup technologies around is Yahoo! Pipes.  It's a web-based application that enables you to visually create new web apps by aggregating web feeds and other web services in new ways.  Much like you could create pipes and filters to deal with text on Unix, this enables you to do the same with data coming from web sites. Tim O'Reilly called it "a milestone in the history of the Internet" which is pretty high praise from the guy who coined Web 2.0.  Our MySQL community manager Jay Pipes (no relation :-) worked with one of Yahoo's top MySQL gurus Jeremy Zawodny to arrange to get the guys from Yahoo Pipes into a keynote spot at the …

I just downloaded Wordpress to play around with. However, installation failed pretty miserably. The nature of the error messages led me to believe Wordpress does not like the SQL_MODE setting of my lcoal MySQL database.

By default, I have a fairly restrictive SQL_MODE for my local database server, which is set up by this line in my my.cnf option file:

sql_mode=TRADITIONAL,ANSI_QUOTES,PIPES_AS_CONCAT,IGNORE_SPACE,NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION  

Now, a lot of people don't know you can …

I’ve been playing more with the SHOW PROFILE command available as part of MySQL Community 5.0.37. Thanks to the author Jeremy Cole. This command can provide some interesting insight into the workings of MySQL. It does however like most new releases of software enable users to make suggestions for new features and functionality. Here is my wish list. Some I figure are practical, some are wish list, but if you never ask you never know.

1. The Unit of measure for duration is Second. It would be great if it could be tuned for display, say millisecond. If you look at my first Example, all figures are effectively represented in milli-second or even micro-second granularity. …

Nine dollars (US) of Water (how many hours would somebody on minimum wage have to work to buy this 1.5L of water?):

Apart from that, jetlagged - managed to find food, TV, internet. All good.

I’ll be putting photos up on my gallery (which is running a MySQL Cluster 5.1 backend - with disk data) over at:

http://saturn.flamingspork.com/gallery/v/conf/mysql2007/

I just pushed out a significant release of the Amazon AWS S3 MySQL storage engine. There are significant stability, performance, debugging, and feature improvements.

Available via

http://hg.fallenpegasus.com/
http://fallenpegasus.com/code

Unless there are any showstoppers, this is the one that is going to the MySQL Expo next week, to be presented on Wednesday.

http://www.mysqlconf.com/cs/mysqluc2007/view/e_sess/10822

It allows one to view and manipulate Amazon's S3 storage service as tables and items by MySQL. You can keep your blobs or large varchars or truely huge datasets in S3, and then join the tables against your local ones.

If you're a …

Here is the perl script referred to by mysql-memory-usage-profile.

Downloadable: mysql_memory_profile.pl

#!/usr/bin/perl
# Version: 1 Last Change by: procter.pythian. 20070419 14:14:39
# Copyright 2007, The Pythian Group, Inc. All rights reserved.
# Hey, we work hard on this stuff!

# Feel free to use this script, un-modified, as much as you like 
#on any system. If you find issues or have comments, we would 
#welcome the opportunity to collaborate with you on it. But we 
#haven't yet decided on any formal licensing (GPL etc.) and 
#public interest will be a factor on whether we go that route.

# MySQL Memory Profiling Script

# Reference: http://www.pythian.com/blogs/431/mysql-memory-usage-profile

#MD5 Checksum 5D713DCA3702EBC91D3B1AA997E68F07 …

PBXT is a transactional storage engine, but what does the design have in common with MyISAM?

I'll be answering this and other questions during my session at the MySQL Users Conference next week:


PrimeBase XT: Design and Implementation of a Transactional Storage Engine
Date: Wednesday, April 25
Time: 10:45am - 11:45am
Location: Ballroom F


So be sure to check it out! :)