How do you like your SQL served? Personally I like this type:

SELECT   dc.state
       , dd.year
       , dd.month
       , sum(fs.sales) as total_sales
FROM     fact_sales     fs,
         dim_date       dd,
         dim_customer   dc
WHERE    fs.customer_tk = dc.customer_tk
AND      fs.date_tk     = dd.date_tk
AND      dd.year IN ( 2006, 2007 )
GROUP BY dc.state
       , dd.year
       , dd.month

Obviously, it’s inspired by simple star schema querying. Anything goes for me, but I kinda like a little bit of “structure” in my SQL (no pun intended), just a little bit of overview.

What’s your favorite SQL format?

Matt

P.S. We will soon be launching PDI version 2.5.0, stay tuned!

This is the second part of the "Howto write a FindBugs Bug Detector" (see the first part here). To understand why one would write the kind of detector mentioned here, you should read the first part if you do not already know it.

Last time I presented a detector that is able to detect static fields of the types java.util.Calendar and java.text.DateFormat. While declaring fields like this may be suspicious, there is not necessarily something wrong with the code. The real danger comes from calling methods on suchlike fields, especially if they are not synchronized to protect them against concurrent access. So in this article we will extend and improve the existing detector to cope with this problem.

Something to chew on

This a simple class that uses a static Calendar instance. It does not …

This is the second part of the "Howto write a FindBugs Bug Detector" (see the first part here). To understand why one would write the kind of detector mentioned here, you should read the first part if you do not already know it.

Last time I presented a detector that is able to detect static fields of the types java.util.Calendar and java.text.DateFormat. While declaring fields like this may be suspicious, there is not necessarily something wrong with the code. The real danger comes from calling methods on suchlike fields, especially if they are not synchronized to protect them against concurrent access. So in this article we will extend and improve the existing detector to cope with this problem.

Something to chew on

This a simple class that uses a static Calendar instance. It does not …

Now that you can load an engine, we are going to look at reading data. For this we will need to implement three methods. We will also need the following schema:

CREATE TABLE `services` (
`a` varchar(125) NOT NULL DEFAULT '',
`b` text
) ENGINE=SKELETON DEFAULT CHARSET=latin1



Storage engines provide "handler" objects that are used to read/write/update tables. They inherit from the handler class defined in sql/handler.h.
The file ha_skeleton.cc holds the implementation of the handler for the Skeleton engine. Once a handler object is created it is cached and can be used for different tables that a particular storage engine controls. MySQL uses the open() and close() methods of handler object to tell the handler what table it should currently work with.

open() and close() are not called for each usage of a table, or each usage of a transaction.

For …

We just finished up our 2007 Users Conference and I'd really like to thank David Sceppa and Jeffrey McManus for presenting at the conference.  David is a program manager on the ADO.Net team at Microsoft and I had more than one person come up to me and tell me that having a Microsoft rep at the sessions really indicated that we were serious about working with Microsoft tools and that Microsoft seemed very willing to help with that.  True indeed.

Also, I really appreciated Jeffrey being willing to jump in last minute and do a presentation for us.  He does alot of traveling and presenting so I know his time is precious.  Jeffrey also recently made available a tool he wrote for generating a set of classes for a given database schema.  He calls it Cgen and you can read his announcement about it here.  Keep up the good …

Today everybody writes about MySQL Conference & Expo and I am not an exclusion. I am under impression of count of storage engines were presented. In good old time when Oracle bought InnoDB, MySQL did one step - announced MySQL supports Plugginable Storage Architecture. In that time nobody was able to predict what is the outcoming of such feature, but currently we all see it.
Let me list Transactional Storage Engines I heard of on Conference and main impression about.
InnoDB On the conference InnoDB presented two new interesting features - transparent ZIP of pages stored on disk. Potentially it can imporove performance of tasks with intensive I/O load a lot. Second feature - fast index build. Both should be available in 5.2 MySQL.
PBXT Interesting engine, mainly because of way to store new records "never updates" and just write to the end of file. Surely it has as benefits as and drawbacks. We are …

Last week during the MySQL Conference I took part in the MySQL Quiz Show. Five groups of MySQL staff (or related) trying to guess the answers of questions proposed by three judges in a funny and easy going environment. Frankly, I thought it was going to be all database techie stuff, but actually most of the questions were quite affordable for the average geek mind. Besides, not always the right answer would give you the most points. Sometimes answering something witty would give a good reward, and would make the quiz more creative and enjoyable. And bribing the judges with beer could lead to the definite path to victory I really enjoyed it!

I managed to take some pictures and videos, though the quality is pretty low …

Didn't make MiX '07?  Neither did I.  That's ok, though, cause the sessions are all online here.  Alot of great content here.  I'm listening to a session talking about PHP on Windows.  Gotta get back....

I'm supposed to be working on subquery optimization but I can't get BUG#26630 out of my head.

The bug test case is small and easy to understand: looking at the EXPLAIN:

CREATE TABLE tbl_test( ... ) partition BY range(num) (...);
 
EXPLAIN partitions
SELECT * FROM tbl_co c STRAIGHT_JOIN tbl_test t WHERE t.num=c.num AND reg=8;

..+-------+-------------+------+---------------+------+---------+------+------+-------------+
  | table | partitions  | type | possible_keys | key  | key_len | ref  | rows | Extra       |
..+-------+-------------+------+---------------+------+---------+------+------+-------------+
  | c     | NULL        | ALL  | NULL          | NULL | NULL    | NULL |   17 | Using where |
  | t     | p0,p1,p2,p3 | ALL  | NULL          | NULL | NULL    | NULL |   17 | Using where |
..+-------+-------------+------+---------------+------+---------+------+------+-------------+ …