MySQL stored procedures can use SELECT statements in their body, returning a data set to the caller. The manual also explains that multiple data sets can be returned from such a stored procedure.
For example, assume you have this stored procedure:

CREATE PROCEDURE p1(x INT, y INT)
    DETERMINISTIC
    BEGIN
        SELECT 
            x ;
        SELECT 
            x AS first_param, 
            y AS second_param;
        SELECT 
            x, 
            y, 
            x + y AS sum_xy, 
            x * y AS prod_xy; 
        SELECT *  FROM t1;
    END

There are four SELECT statements, with different headers, and a variable number of rows returned.
Early versions of …

I've got an interesting comment the other day saying "I've heard Jay Pipes saying indexes with cardinality lower than 30% are worthless, true?"

That is interesting question and it has different answers depending on who is asking. A lot of people want to hear simple answers to the questions because they would be overwhelmed by complete answer, it is like children being taught math first taught simple division skills like you can divide 10 by 2 but not by 3. As we grow up we learn the truth is much more complex than that and if you Major in math you will find there is a lot of stuff out where far beyond basic stuff we use in every day life.

Answering such question you can say yes it is true and for clueless person it will be helpful answer because it will allow him to avoid creation indexes on the column containing just one value which is good idea.

If you start to explain it in details, a lot of variables add in - covering …

I have put together a list of the sessions that are of interest to me this year at the MySQL Conference. Again, there is some overlap in sessions I would like to do, particularly with some certification exams in there as well! :)

• Building Scalable OLAP Applications with Mondrian and MySQL - Because I have been working with this and want to learn more.
• Building a Vertical Search Engine in a Day - Because I like to compare search engines.
• InnoDB Performance Potential in High-end Environments - Because I am always interested in high-end environments and performance.

One of the cooler bits of technology I got to see while in Japan last week was a MySQL Storage Engine for doing fulltext searches in Japanese. The engine in question was Senna, and it was merged with the MyISAM engine.

Fulltext for Japanese is hard, its a very non-trivial problem. The Senna developers are some of the many different storage engine vendors who will be at the MySQL User's Conference in a couple of weeks.


Tritonn (Binding between MySQL and Senna)
http://qwik.jp/tritonn/

Presentation Material(in Japanese)
http://www.scs.co.jp/mysql/docs/OSC2007SpringTokyo_MySQL_Senna.pdf

You can download it …

I'll present a session on the innotop MySQL and InnoDB monitoring tool at 2007 MySQL Conference and Expo in a couple of weeks.

The innotop session will focus on using innotop's basic and intermediate-level features. I'll demonstrate how to install it and get the initial configuration set up. I'll show you what innotop is good at doing, and how to do some of the things I do frequently, such as watch queries, check replication status, and look at what transactions are currently open. And I'll demonstrate some of innotop's many small features that can help you use it to watch and control your MySQL servers.

You'll leave the session with a comprehensive …

Here is a quick heads up for those following along in the buzz-meter generated about the MySQL Conference and Expo in a couple weeks: the development team responsible for Yahoo! Pipes — the incredible web-based GUI for mashing mashups — will be doing the conference's closing keynote... more details to come!

Anyway, I wanted to follow up on Kaj's blog post about the "Clash of the DB Egos" scheduled for Wednesday morning, directly following Eben's "Freedom Businesses Protect Privacy" keynote talk. In Kaj's original post, he joked that E.F. Codd and …

Event Information

Topic:
Backup and Recovery of MySQL Clusters

Date and Time:
Thursday, April 12th , 2007 10:00 am
Pacific Daylight Time (GMT -07:00, San Francisco)

Panelist(s) Info:
Shailen Patel - Professional Services Engineer,
Paddy Sreenivasan - VP, Engineering,
Ram “TK” Krishnamurthy - VP, Services and Support

Duration: 1 hour

Description:
Zmanda Recovery Manager [ZRM] for MySQL provides a simple and easy way to backup and recover MySQL clusters. Zmanda Engineers will provide an overview of ZRM for MySQL and demonstrate its ability to backup and restore MySQL cluster.

This year I am looking forward to the MySQL Conference mostly because I get to hook up with old friends and co-workers, but of course I also plan to sit in on a few sessions:

• MySQL Sandalcamp: A Relaxed Intro to MySQL - Because Zak is a great speaker.
• MySQL at Digg.com - Because I like to hear about scaling MySQL.
• InnoDB Performance Potential in High-end Environments - Because I’m a sucker for Japanese presenters
• Intro to MySQL Cluster - Because I need to know more about cluster (and Stewart’s a cool …

Looking at how people are using COUNT(*) and COUNT(col) it looks like most of them think they are synonyms and just using what they happen to like, while there is substantial difference in performance and even query result.

Lets look at the following series of examples:

PLAIN TEXT SQL:

1. CREATE TABLE `fact` (
2.   `i` int(10) UNSIGNED NOT NULL,
3.   `val` int(11) DEFAULT NULL,
4.   `val2` int(10) UNSIGNED NOT NULL,
5.   KEY `i` (`i`)
6. ) ENGINE=MyISAM DEFAULT CHARSET=latin1
7.  
8.  
9. mysql> SELECT count(*) FROM fact;
10. +----------+
11. | count(*) |
12. +----------+
13. |  7340032 |
14. +----------+
15. 1 row IN SET (0.00 sec)
16.  
17.  
18. mysql> SELECT count(val) FROM fact;
…

In two weeks from now, the MySQL Conference & Expo 2007 will take place in Santa Clara, California. Our team has been very busy with working with the conference management team from O'Reilly to prepare for this event, especially Jay who is in charge of organizing and arranging the more than 110 sessions that will be held in several parallel tracks. The conference program looks very exciting, I am impressed by the wide range of topics and quality of speakers that we have lined up.

In addition to the presentations and tutorials, there will also be an Expo, where partner companies will exhibit their products …