With this post, I am starting another series of blog posts that will help you become familiar of DTrace. You can then apply that knowledge to find all the hidden performance goodies of MySQL on Solaris 10. Sounds good?

DTrace is one of those tools that the more you use it, the more you fall in love with it. To be fair, it is much more than a tool, in fact it has its own language, D.

With DTrace you can enable probes by either their name or their number. To see a list of probes available, run

[root@db31:/] dtrace -l | more
   ID   PROVIDER            MODULE                          FUNCTION NAME
    1     dtrace                                                     BEGIN
    2     dtrace                                                     END
    3     dtrace                                                     ERROR
    4    syscall                                               nosys entry
    5 …

I've semi-started a lot of blogs, will this one last?

My name is Jay Janssen. Amongst other things I am a MySQL guy (tm) at Yahoo! This is a role that I more fell into, rather than one I specifically applied for. My background is Operations, somewhere between Coding/Developing and a System Admin/Colo Tech. I've done both, to some extent, and what's great about Yahoo is finding a lot of opportunity to set stuff up, see it run and fix it when it breaks.

MySQL, of course, never breaks. Unfortunately this only really true most often for the blogger, the guy on the hosted website or on an old P-III 1 Ghz running Debian Sarge off of his cable modem. These are the guys who don't know what hit them when digg.com comes around. In reality, the true test of any software is what happens when you beat the …

The 3rd Barcamp Brussels is over, I was a bit dissapointed over the target audience of the first Barcamp, missed the second one, but the 3rd one was right where I expected it to be A healthy mix of technology, startup projects and the social aspect of technology.

I took my Tuxdroid with me, planned on having him tell the audience what they were twittering about, the idea was to take the logfile of my twitter jabber session and feed that to the text to speech deamon into Tux. I failed due to the lack of network hence incoming twitter stream, however the Tuxdroid proudly whacked its wings at the end of each talk :)

So about those talks :)

After Peter gave the startshot for the fight …

While there is quite a bit that can be done with read only engines, writing data is entirely more fun :)

For our next lesson we are going to be doing exactly that. Unless you are writing a blob store only engine you will need to deal with fields, aka the columns you declare with a create table. Placing these fields into some sort of format is required. Different engines implement different written forms to disk. Most transactional engines work in block formats, while stream designs are common for engines which need high write performance.

There is no one right way to implement storage on disk, every design has a trade off.

Let us look at XML. It is slow to parse and slow to read. XML though is adored by many because it is a simple format that can be ready by many applications.

For our example we are going to put together an XML engine, and to that end we will use the …

Man, I can't believe it's been over a week since I returned from the very great and exciting MySQL conference 2007. I got to meet all my old and new friends. Big Kudos to Jay Pipes and all MySQL'ers who helped make this event possible.

To me, this year's conference was the best ever. Partly because I made the very wise decision of staying at Hyatt so I won't miss a lot. At conferences like these the more you mingle with people, the more you get out of it. I had some amazing conversations with Mark Atwood, Brian Aker, Jay Pipes (I will never forget :)), Jeremy Cole, Eric Bergen, Pascal (Yahoo! France), Beat Vontobel, Markus Popp, Boel (MySQL HR), Christine Fortier, Marc Simony, Govi (Amazon), the "R"s of MySQL (Ronald and Ronald), Sheeri Kritzer, Carsten (certification), Ken Jacobs (Oracle), Kaj Arno, Dean (MySQL Support head), Domas, Kerry Ancheta (MySQL sales guru :)), Baron, Paul Tuckfield, Don MacAskill, Tobias, Peter Zaitsev, Chip …

I’ve talked to several people that have questions about how alter table works under the hood. They want to know how it handles locking tables why they can sometimes use a table during alter table and other times they can’t. Also why it’s so slow

First let’s look at the basic process alter table typically goes through.

1. If a transaction is open on this thread, commit it.
2. Acquire a read lock for the table.
3. Make a temporary table with new structure
4. Copy the old table to the temporary table row by row changing the structure of the rows on the fly.
5. Rename the original table out of the way
6. Rename the temporary table to the original table name.
7. Drop the original table.
8. Release the read lock.

The slowest part of the process is copying rows from the original table to the temporary table. For large tables this can take minutes …

Yes, I know there are a lot of software development "top n" lists out there, and many dealing with writing "-[i/a]ble" software (extensible, maintainable, saleable, etc), but personally I wanted to get these concepts that have been rattling around in my brain for sometime down somewhere and hopefully start a discussion around them. Even though this isn't a wiki, I'll probably end up treating this like a living document myself.

For a long time (in software years), I've been maintaining the code base for the JDBC driver for MySQL. I also work very closely with the support team on various connectivity-related issues (JDBC, ODBC, ADO.Net, P-this-or-that, etc.) that our customers have, and have had the (mis)fortune of debugging all kinds of problems in various stacks over the years.

Sometimes we (MySQL) make debugging more of a problem than it needs to be, and sometimes it's just inherent problems in the "stack". Given that I …

Yes, I know there are a lot of software development "top n" lists out there, and many dealing with writing "-[i/a]ble" software (extensible, maintainable, saleable, etc), but personally I wanted to get these concepts that have been rattling around in my brain for sometime down somewhere and hopefully start a discussion around them. Even though this isn't a wiki, I'll probably end up treating this like a living document myself.

For a long time (in software years), I've been maintaining the code base for the JDBC driver for MySQL. I also work very closely with the support team on various connectivity-related issues (JDBC, ODBC, ADO.Net, P-this-or-that, etc.) that our customers have, and have had the (mis)fortune of debugging all kinds of problems in various stacks over the years.

Sometimes we (MySQL) make debugging more of a problem than it needs to be, and sometimes it's just inherent problems in the "stack". Given that I …

Yes, I know there are a lot of software development "top n" lists out there, and many dealing with writing "-[i/a]ble" software (extensible, maintainable, saleable, etc), but personally I wanted to get these concepts that have been rattling around in my brain for sometime down somewhere and hopefully start a discussion around them. Even though this isn't a wiki, I'll probably end up treating this like a living document myself.

For a long time (in software years), I've been maintaining the code base for the JDBC driver for MySQL. I also work very closely with the support team on various connectivity-related issues (JDBC, ODBC, ADO.Net, P-this-or-that, etc.) that our customers have, and have had the (mis)fortune of debugging all kinds of problems in various stacks over the years.

Sometimes we (MySQL) make debugging more of a problem than it needs to be, and sometimes it's just inherent problems in the "stack". Given that I …

this time it only took two months since the last release ? mysql connector/odbc 3.51.15 is now available. there aren?t a lot of bugs fixed in this release, compared to the 150 or so open bugs, but it is nice when you get to close a bug that is nearly three years old.

i?m not sure when the next release will happen, but i already have one patch pending.