MySQL does not always make a right decision about indexes usage.
Condsider a simple table:

PLAIN TEXT SQL:

1. CREATE TABLE `t2` (
2. `ID` int(11) DEFAULT NULL,
3. `ID1` int(11) DEFAULT NULL,
4. `SUBNAME` varchar(32) DEFAULT NULL,
5. KEY `ID1` (`ID1`)
6. ) ENGINE=MyISAM DEFAULT CHARSET=latin1

SELECT COUNT(*) FROM t2;
250001 (V1)

SELECT COUNT(*) FROM t2 WHERE ID1=1;
83036 (V2)
(execution time = 110 ms)

That is index selectivity by condition (ID1=1) is V2/V1 = 0.3321 or 33.21%

It is said (e.g. book "SQL Tuning") if selectivity over 20% then a full table scan is preferable than an index access.
As far as I know Oracle alway chooses a full table scan if selectivity over 25%.

…

Finally i was able to do a benchmark of the 3 search engines
- mysql fulltext search
- lucene search engine
- sphinx www.sphinxsearch.com

I came across sphinx while doing a search on full text search engines. It is a very good engine. Few points regarding sphinx
-> Very simple to configure, create index and search
-> Very easy to integrate with php and mysql. APIs for the same are also available. I was able to build index and search using sphinx in a few hours.
-> The index which has been created is a combination of all fields of mysql. There is no distinction between different fields being searched. So you can perform search on an index and not on different fields of the index.
-> Of course since its source code is available, the searching process can be customized according to your needs. Moreover 0.9.6 version …

Paul McCullagh works on a new pluggable transactional Storage Engine for MySQL, called PrimeBase XT. I met him for an interview a few days ago - you can now read it on the MySQL Developer Zone. Enjoy and have a nice weekend!

Let's say that you are building a new application, and you need to test it against a large set of data. You would need either to borrow the data from some known source or to create it yourself.

If you have such collection at your disposal, good for you. But more often than not you need some sort of data that is not ready in your repositories, and then you need to have a quick method to create it.

I will tell you three quick tricks to create large datasets of simple data types, namely numbers, words, and dates.

Le's assume that we need at least one million records. Here's how to go for it.

numbersCreating a large table with just a numeric field is quite simple.

You may be tempted to run a loop in your favorite language, or even in a SQL stored procedure, but this approach would run for quite a long time.
There is a better …

The PrimeBase XT Storage Engine (PBXT) is a new transactional database engine for MySQL. It has been designed for modern, web-based, high concurrency environments. In May 2006, I had the opportunity to meet with Paul McCullagh, the head developer of PBXT for lunch at the Hamburg offices of Snap Innovation GmbH, the company behind PrimeBase. It was co-founded by Paul in February 1996 and is focussed on the development and sales of client/server database technology, specializing in inter- and intranet systems.

Notice something new?

Ok, I made that one easy for you. Thanks to the MySQL AB web team there is finally a tool for flipping between the same page in the different version manuals.

Thanks Markus!

FORTUNE: Banish the HQ

“Few businesses are as spread out as MySQL, which employs 320 workers in 25 countries, 70 percent of whom work from home.”

Red Hat kicked off their Summit in Nashville with over 800 attendees.  It appears that the conference is larger than last year, though still not as large as the MySQL Users Conference in April. (We had over 1,600 attendees this year.)  Red Hat has put together an excellent conference program with a broad range of speakers including Nicholas Negroponte (MIT Media Lab), Eben Moglen (FSF), Cory Doctorow (EFF).  Also, they've open up the program this year to promote Red Hat partners including MySQL, ActiveGrid, Alfresco, Zimbra, Zend and others.  MySQL's Jay Pipes and Nicolas Pujol will be doing a presentation on MySQL scale-out on Red Hat Enterprise Linux.

Here are a few good links …

Patrick released a new version of the perl MySQL connector. This .pm was my introduction to the mysql world, way back in the day. If you can program your way out of a perl brown paper bag and you haven’t used this tool yet, I recommend you write a hello world program to get familiar with it. Good stuff.

Dear DBD::mysql users,

This announcement comes a few days late, but DBD::mysql version 3.0004
(stable, production) and 3.0004_1 (dev) have been released!

Version 3.0004 is the production version with server-side prepare
statements turned off by default, and 3.0004_1 is the development
version with server-side prepare statements turned on by default.

The changes in 3.0004, as listed in the changelog:
  * Fix dbd_st_finish which closed the handle prematurely (Martin Evans)
  * Compile issues (Martin Evans)
  * Fix to dbd_bind_ph to deal with numbers (ints, floats) correctly
    (Alexey Stroganov)
  * Test changes - bind_param 41 and 42

The changes to …

Dear MySQL users, MaxDB users and friends,

we have moved the MaxDB series to the MySQL Developer Zone. The latest issue on Transactions is available on http://dev.mysql.com/tech-resources/articles/maxdb-transactions.html . Additionally you can download a PDF document (1.86MB, 64 pages) with all articles published in the MaxDB series for offline reading and printing.

Feedback on the MaxDB series and on MaxDB in general is always welcome. Please use the MaxDB forum to send in your comments and questions.