Wikimedia Foundation is expanding Wikipedia to multimedia with Sun Open Storage Solution and MySQL Database:

Wikipedia receives between 25,000 and 60,000 page requests per second, depending on the time of day. Wikimedia needed to update its infrastructure to handle this huge volume of traffic and ensure that its systems were reliable, highly available, and easily scalable. It also wanted to expand its upload file limit from 20 MB to 100 MB to accommodate rich media (audio and video) content, but before it could do that it needed to expand its storage capacity.

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My presentation at LOSUG on tuesday went down like a house on fire - I think it would be safe to say that the phrase for the evening was ‘It’s a cache!’.

For that to make sense, you need to look at the slides, which are now available here.

Attendance was great, but it seems the last minute change of day meant that some people missed the session. We had 151 people register, and about 80 turned up on the night.

« Post 3 | This is the 4th post in my MoFo Futures 2009 blog series

“When I was a child, my mother lectured me on the evils of ‘gossip.’ She held a feather pillow and said, ‘If I tear this open, the feathers will fly to the four winds, and I could never get them back in the pillow. That’s how it is when you spread mean things about people.’ For me, that pillow is a metaphor for Wikipedia.” — John Seigenthaler Sr.

So the future pulled up in her shiny big metaphor and we got in. In the beginning, our road trip made sense, all well-ordered highways and wholesome roadside attractions. Somewhere along the way, we hit bat country and the …

I’ve been asked about this and realized that it may not be obvious to people who are more familiar with Windows than with Ubuntu. So here is a tip.

When learning MySQL on Ubuntu, it is helpful to be able to get to MySQL’s data directory and observe file creation and modification while you are performing database and table creation and modification, index creation and modification, etc. You can find out MySQL’s data directory by running:

show variables like ‘datadir’;

Suppose your datadir is /var/lib/mysql. And suppose you have a database called test. After opening a terminal window and type:

cd /var/lib/mysql/test/

You will likely receive an error like below:
bash: cd: /var/lib/mysql/test/: Permission denied

Now if you try the command below, as it seems logical on Ubuntu

sudo cd /var/lib/mysql/test/

You will likely get this message:

sudo: cd: command …

Executive summary: There is now a MySQL Room on FriendFeed, as well as a identi.ca group for mysql. Community members, developers, dabblers, users, etc. should find these extra avenues useful, in addition to the forums, mailing lists, and even the Forge. Join them now!

There has been a recent uptake of Twitter amongst the MySQL community… Early adopters have been around for ages, even (as we’re slowly approaching Twitter’s third birthday).

However, I’ve been noticing that slowly, …

Linux kernel uses a number of advanced keywords, macros, and extensions to C language. Here is a description of some of these keywords, macros and extensions that I found troublesome to understand and had to investigate a little bit in order to understand them.

I have used kernel versions 2.4.18 or 2.6.0 for this tutorial.

#define MAX_FIELDS 4096 /* Limit in the .frm file */

I should be able to remove this limitation soon. Although if you come anywhere near it, you probably have already lost (and written your own engine).

Baron was just writing about problems with the Debian init scripts. The basic problem boils down to /etc/mysql/debian-start running mysqlcheck on every table.

Kolbe Kolbe and Harrison Fisk pointed this  out to me last February, and as a result I re-wrote the debian-start.inc script to only operate on MyISAM tables. Additionally, the default config was changed to turn on the myisam-recover option, so even for the MyISAM tables, all we do is touch the table to get MySQL to recover it if needed. (Which I promise you, you really want if you're modifying MyISAM tables on a production server. Don't do that, really, but that's another issue.) The new process essentiall looks like this:

for table in `select TABLE_NAME from information_schema.TABLES where ENGINE='MyISAM'":

  select count(*) into …

Baron was just writing about problems with the Debian init scripts. The basic problem boils down to /etc/mysql/debian-start running mysqlcheck on every table.

Kolbe Kolbe and Harrison Fisk pointed this  out to me last February, and as a result I re-wrote the debian-start.inc script to only operate on MyISAM tables. Additionally, the default config was changed to turn on the myisam-recover option, so even for the MyISAM tables, all we do is touch the table to get MySQL to recover it if needed. (Which I promise you, you really want if you're modifying MyISAM tables on a production server. Don't do that, really, but that's another issue.) The new process essentiall looks like this:

for table in `select TABLE_NAME from information_schema.TABLES where ENGINE='MyISAM'":

  select count(*) into …

So what happens if you want to use the mysql functions AES_ENCRYPT / AES_DECRYPT to handle data encryption, but you might also need to write a tool that takes the encrypted data and accesses or updates it outside of the database? This operation can be hit or miss depending on your library's implementation of how it handles the encryption key passed to the actual encryption function. There is no standard on how this is handled.

AES only defines that it accepts an encryption key of AES_KEY_LENGTH/8 bytes. So for 128 bit encyption you need to give it a 16 byte key.

In mysql you can do:
AES_ENCRYPT('mykey','here is a string to encrypt');

But we just passed it a 5 character string, where does the 16 byte key come from? This is the part that can differ between libraries. MySQL takes your string and converts it like this:

static int my_aes_create_key(KEYINSTANCE *aes_key,
enum …