Twitter has had many outages recently. On May 17th, 2008 http://blog.twitter.com/2007/05/devils-in-details.html was posted and says:

What went wrong? We checked in code to provide more accurate pagination, to better distribute and optimize our messaging system?basically we just kept tweaking when we should have called it a day. Details are great but getting too caught up in them is a mistake. I’ve been CEO of Twitter for two months now and this an awesome lesson learned. We’re seeing the bigger picture and Twitter is back. Please contact us if something isn’t working right (with Twitter that is).

(in other news, that post was made on May 17th and does not show up on http://blog.twitter.com, which it should, between the May 16th and May 19th posts. I found a reference in other …

As announced by Eduardo, I have started playing with The Aquarium.
That does not mean that I sleep with the fishes, but that I am playing along with the group. And besides, dolphins are not fishes, but nonetheless they should be at ease in an aquarium.

This blogging is part of MySQL integration in Sun. Slowly but surely we are becoming aware of our surroundings and we are engaging the rest of the Sun communities.

We are learning.

At this weeks' geekdinner some people wondered what was up with T-Dose, and guess what .. their CFP has been out for ages.

Last year I just catched the end of Bert's talk and Some Abstract Type has also been spotted there before.

No reason to miss this year's edition.

One of the things people tend to forget is the ability for web servers to compress content before sending it back to client. Client’s browser then uncompresses the data and displays it to the user. Pretty much all of the recent browsers support gzip compression. In this post, I will go over how to setup apache2 to use compression. First let’s see if your Apache installation has “deflate” enabled. You can check to see if you have deflate by typing:

# /usr/local/apache2/bin/apachectl -t -D DUMP_MODULES
Loaded Modules:
...
deflate_module (static)
...
Syntax OK

If you don’t have have deflate_module, you would have to recompile your apache with “–enable-deflate” option.

Going forward, I am going to assume you have deflate_module. Add the following to your apache conf file:

<Location />
SetOutputFilter DEFLATE
BrowserMatch …

Following a link from the High Scalability blog, I found this really great article about scalability practices, as told by Randy Shoup at eBay. Randy is very good at explaining some of the more technical aspects in more or less plain English, and it even helped me find some wording I was looking for to help me explain the notion (and benefits) of functional partitioning. He also covers ideas that apply directly to your application code, your database architecture (including a little insight into their sharding strategy), and more. Even more about eBay’s architecture can be found here.

Storage Snapshots are excellent tools in arsenal of a system administrator to create quick and consistent backups of their databases and applications. Snapshot is a “picture” of a filesystem at a point-in-time. In most modern snapshot implementations, this “picture” is not a full copy of the data, but rather a set of pointers to the data.

Here is a list of current industry leading snapshot technologies:

• LVM Snapshots: Snapshot capability built into the Linux Volume Manager (LVM) - the default option on a Linux system.

• ZFS Snapshots: Snapshot capability built into the ZFS filesystem on Solaris and OpenSolaris

• NetApp SnapShots: A feature of the WAFL® (Write Anywhere File Layout) filesystem

• Windows VSS: Volume Shadow Copy Service from Microsoft introduced in …

I am happy to announce that the first Workbench plugin written by the community was published recently.Daniel Haas has written a code generation plugin for Propel, a database abstraction layer for PHP. You can download the plugin from Daniel’s blog that can be found here it is published under the GPL. He also provides the necessary steps to install the script. This is amazing in several ways. First, we have not yet published a comprehensive tutorial how to write plugins and scripts for Workbench because we have been fully loaded with other stuff. Vlad did a tutorial on this at the MySQL Users Conference but the Wiki pages have not been written yet. So Daniel took the hard way, figuring out a lot of things all by himself. Second, we are working on a better …

We introduced a new library to use with our update-feature inside Workbench. With the new lib (yassl) it’s possible to use SSL encryption for the authentication/download of new SE releases. This was not possible with libcurl because we’re not allowed to use/bundle openSSL. As this update is included staring with 5.0.22 all SE users will have to download version 5.0.22 manually from the enterprise pages one more time. Please logon to https://enterprise.mysql.com/software/gui_tools.php with your mysql username and password, download the latest release and launch the installer manually. Sorry for the inconvenience.

The parameter DiskSyncSize is a MySQL Cluster parameter and was added in MySQL 5.1.23.

After the amount of stored bytes of data per file, the data node will fsync (flush) the LCP file to disk, even if a fsync is not needed for consistency.
This is done because the OS will otherwise buffer all the writes, and when a fsync is really needed, it can take a lot of time...

Originally this parameter was hard coded. Now it defaults to 4 Mbyte.

The parameter DiskSyncSize is related to the parameters NoOfDiskPagesToDiskAfterRestartTUP and NoOfDiskPagesToDiskAfterRestartACC which are deprecated right now. It does NOT replace the parameter TimeBetweenLocalCheckpoint.

This parameter should not be changed on any OS (with reasonable settings). With ODIRECT it is not used at all.

Thanks to Jonas for the help.