Translation of "Chapter 3. Wrong data in database or what to do with problem DML query." of  "Methods for searching errors in SQL application" just published.

 This is short chapter which discuss single method of dealing with mysterious DML query.

Chapter 3. Wrong data in database or what to do with problem DML query.

Problems with wrong data happens not only with SELECT queries like
cases we discussed in chapter 2, but in cases of querires which modify
data: DML queries.

Lets discuss example below

mysql> create table t1(f1 int);


Query OK, 0 rows affected (0.01 sec)

…

In my last post, I discussed how fractal tree data structures can be up to two orders of magnitude faster on deletions over B-trees. I focused on the deletions where the row entry is known (the storage engine API handler::delete_row), but I did not fully analyze how MySQL delete statements can be fast. In this post, I do. Here I show how one can use TokuDB, a storage engine that uses fractal tree data structures, to make MySQL deletions run fast.

Let’s take a step back and analyze the work needed to be done to execute a MySQL delete statement. Suppose we have the table:

create table foo (
        id auto_increment
        a int,
        b int,
        primary key (id)
)

Say we wish to perform the following operation that deletes 100,000 rows:

delete from foo where a=1;

In MySQL, …

While I have spent a lot of time recently helping the MySQL community interact with and integrate with various Oracle User Groups including ODTUG, IOUG, NoCOUG, NYOUG, DAOG I thought I’d share some resources for the MySQL Community that wanted to know more about Oracle.

The Oracle family of products is huge. You only have to look at the acquisitions via Wikipedia to get an idea. The first thing is to narrow your search, e.g. Database, APEX, Middleware, BI, Hyperion, Financials, development via Java, PHP or Oracle Forms etc.

While Oracle is a commercial product you can download all software for FREE via Oracle Technology Network. There is also documentation, forums, blogs and events.

Some Oracle bloggers I have already been reading however I’m expanding my list. People you may want to …

After the acquisition of Sun by Oracle, Oracle had made a commitment to put together a MySQL Storage Engine Advisory Board. Over a month ago, Infobright was invited to join the Oracle MySQL Storage Engine Advisory Board and last week was the first in a series of meetings that Oracle will be hosting for the Advisor Board members. Oracle did a terrific job stepping up to the task of assembling a well known group of companies as part of the board. The meeting last week was clearly a sign of commitment by Oracle to work closely with the storage engine vendors in the market. This resonated very well with the advisory board members.

At this initial meeting we all had an opportunity to learn from each other as key storage engine vendors in the market and to also hear directly from Oracle about their plans for MySQL. Senior members of the Oracle team including Edward Screven, Chief Corporate Architect for Oracle attended the meeting where we had a …

After the acquisition of Sun by Oracle, Oracle had made a commitment to put together a MySQL Storage Engine Advisory Board. Over a month ago, Infobright was invited to join the Oracle MySQL Storage Engine Advisory Board and last week was the first in a series of meetings that Oracle will be hosting for the Advisor Board members. Oracle did a terrific job stepping up to the task of assembling a well known group of companies as part of the board. The meeting last week was clearly a sign of commitment by Oracle to work closely with the storage engine vendors in the market. This resonated very well with the advisory board members.

At this initial meeting we all had an opportunity to learn from each other as key storage engine vendors in the market and to also hear directly from Oracle about their plans for MySQL. Senior members of the Oracle team including Edward Screven, Chief Corporate Architect for Oracle attended the meeting where we had a …

Last Saturday I became father to a baby girl - in addition to our 2½year old son.

Those of you who are my former collagues from MySQL, you know about the generous Scandinavian 5 week vacations. (Which in MySQL were practiced globally.) I have decided that now is a good time for me to enjoy another Scandinavian perk: long paternity leave. I will be home with the rest of the family until approximately next February :-)

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Mark’s done an excellent job again, getting VM’s of MariaDB 5.1.47 (release notes, changelog) out there for download. He’s also improved the bandwidth available at the box hosting these images. Get it for Ubuntu 10.04 or OpenSolaris 0906.

Related posts:

1. …

You might be familiar with Six Sigma business management strategy which is employed by variety of the companies in relationship to managing quality of its product. Six Sigma applies to number of defects - when you have reached six sigma quality in your production you would see 99.99966% of the products manufactured with no defects, or in other words there is less than 3 defects per million.

One of principles of six sigma is what customers tend to be concerned about variance a lot more than average. For example if you produce tomato soup and the average difference from declared weight is going to be 0.1 gram or 0.5 gram, probably nobody would not notice the difference. What would worry people however is significant number of very large differences, such as half empty tomato soup can.

You can see …

Wow, 15 years ago, on June 8th 1995, Rasmus announced PHP 1.0. Time for a personal look back:

I can't remember when I first went online. Out from the local BBS systems into the wide open net. It must have been around the same time. But soon I figured out that I needed my own homepage, so I created one, using black fonts on a green (#00ff00) background. I was proud. The only issue: I had no idea how to make it accessible to others, I had the HTML file local on the PC, but well, I still was proud. I was proud since the effect of this HTML with a little bit of JavaScript was way stronger than most of my BASIC stuff I did before.

A bit later, in 1998, a cousin brought a magazine about writing Perl CGI applications which caught my attention so I started learning about CGI and Perl and all the …

A few months ago, I reviewed MySQL Admin Cookbook. Today I am reviewing High Availability MySQL Cookbook from Packt Publishing by Alex Davies. Overall, I found the book to contain some good hidden Gems.

The book is a mixture of MySQL Cluster (NDB), Replication schemes, some performance tuning, some minor kernel tweaking, and some more exotic approaches to common High Availability problems. Overall, I found this book very informative and a good read.
Now the specifics, the book starts out on NDB and stays focused on this fact for about 60% of the book. The next 20% is on mySQL replication then about 10% of the book is on tweaking kernel, mysql, network settings to get the most out of …