In my previous job at Sifira A/S, I developed the first version of chan_ss7.

Chan_ss7 is a module for Asterisk, which interfaces Asterisk to an SS7 network.

So what is SS7? It is the network that runs the worlds telephone network. Chances are that as soon as your phone call reaches the local central (analog/ISDN) or base station (cell phone), it is transported over SS7. SS7 is the domain of big telephone switches from Nokia, Ericsson, and others, and a lot of very expensive and proprietary equipment.

So how does that fit with the world of cheap IP-based telephony and Free software? As it turns out, not bad at all!

Since my …

Shai Agassi, president of SAP's products and technology group said yesterday that he expects MySQL to be certified to run SAP applications by the end of the year.  This is an excellent endorsement not only of MySQL, but of open source technology in general.  SAP R/3 is the benchmark when it comes to the most sophisticated and demanding enterprise application and the testing process is exhaustive (if not exhausting!)  And even for users who may never need to run SAP, it's good to know that MySQL will be able to standup to all the testing.

It's something we've been working on for quite some time with SAP and it's nice to see that the top execs are aware and supportive of our efforts.  Agassi has sometimes been misunderstood in his comments on open source, but in our view, they've always been a huge supporter.

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In general, information_schema is a great thing - you can get all kinds of information out of it in quite a simple way.

But it has a downside - on a server with lots of databases and tables, it can be very slow. However, more and more applications rely on information_schema, and that can be a problem.

I just tried to update phpMyAdmin for db4free.net from 2.7.0-pl1 to 2.8.0.3. The update itself was a smooth thing, but when I tested the new version and tried to open a database, phpMyAdmin just couldn't make it.

So I looked for the cause, and I found it quite quickly. I searched the whole phpMyAdmin directory for the string "information_schema" and there were quite a lot of results. When I did the same for the directory of phpMyAdmin 2.7.0-pl1, there were no results at all.

So while …

On May 3 and 4, 2006, the European Commission and the European Patent Office will jointly present the European Inventor of the Year Conference & Gala.

There is no question that the world in general needs innovation, and so does Europe. I am all for honoring true inventors. However, this particular award series and event looks, at least in part, like an attempt to reinforce some common misconceptions and fallacies concerning innovation policy.

The involvement of the European Patent Office and the selection of nominees based on the patents they received makes a connection between patents and inventiveness that is only half-true at best. While the official and original idea of the patent system is to protect and reward inventors, the reality of more than 180,000 patent applications filed at the EPO per year (and that number is still growing) suggests that the fewest patents …

Jay Pipes (co-author of Pro MySQL) is in town and will speak about “MySQL Performance Tuning Best Practices”. This is the workshop he’ll be giving at the MySQL Users Conference, so if you can’t go don’t miss this meetup! There will be FREE pizza and soda.

We will have giveaways of Pro Mysql and gift certificates for free Apress books, and other swag like T-shirts, buttons, etc. RSVP for a headcount of soda and pizza at http://mysql.meetup.com/137/events/4875276/ (you will have to register; sorry…. ) Mike Kruckenberg will be there, so if you want your copy (or the copy you win!) signed by both authors, you can.

Description of the workshop: Learn where to best focus your attention when tuning the performance of your applications and database …

I have had a great response from people with regards to the (possible) closure of MySQLDevelopment. It seems people want to keep the site alive in one format or another and I have had a lot of communication from MySQL themselves with regard to keeping the content alive.

First let me say sorry to all the people who did respond, as suggested in my last post I am really busy at the moment and it's difficult to find the time to reply in a timely fashion. I will be contacting you all individually this weekend.

Whatever happens it seems that while the site may change a little as from the 1st May MySQLDevelopment will still be available in some form. I'll keep you posted.

I finally got around to working with the 5.1 scheduler.  I wanted to have a simple but non-trivial example, and when I saw Brian Akers post on the new processlist table, I thought of a useful little application:  I would submit an event that would summarize the users and their statuses at regular intervals so I could track user trends.

First off,  I needed to enable the scheduler by adding the following line to my configuration file:

event_scheduler=1

Now the scheduler is ready for action.  So I created a table to hold my process list details:

CREATE TABLE processhistory (h_timestamp DATETIME,
                             processcount INTEGER,
              …

First, a bit of background information… MySQL has a variable called tmp_table_size which is used whenever a temporary table is needed for many types of operations, but it’s mainly used for ORDER BY and GROUP BY. The tmp_table_size variable (in correlation with the max_heap_table_size variable) decide at what point to convert an in-memory (that is, HEAP storage engine) temporary table to an on-disk (that is, MyISAM) one.

So, if the result of your query will end up greater than the lesser of tmp_table_size or max_heap_table_size, once it reaches that point, it will be automatically converted to a MyISAM table, on-disk (in tmpdir, incidentally).

Here’s a scenario: You have a SELECT query, nothing particularly special. It isn’t any more complex than another query on the same tables, but it performs a bit worse. You put some load on it, and it performs miserably, even putting the server in pain in the process. You check what’s …

A friend of mine recently asked me to show him how to enable cascading deletes between tables in MySQL. Cascading updates and deletes can be turned on between tables related with foreign keys in many RDBMSs. Though they can be convenient for some purposes, they can have unexpected side effects, and can be very confusing and dangerous at times. In this article I’ll discuss some of the ways cascades can do invisible things, and show you one place they can be very handy too.

MySQL Bugs: #18866: ndbd segfaults when starting 2 times

Jonas is just incredible, not even 3 minutes after I report a bug he replies to it. It takes me 4 minutes to realise it's actually duplicate, and by the time I want to comment on that myselve I see that he already made the same comment.

No way you can ever get that from a proprietary software company !