Facebook's engg. director aditya talks about facebook architecture. How they use mysql, php and memcache. How they have modified the above to suit their requirements.

There has been some chatter bouncing around the blogosphere and twittersphere that we are deprecating urchin.js sometime this summer. This is not accurate. To be clear: we have no immediate plans to decommission urchin.js. If and when we do, we will make sure users get clear, advanced notification from us and time to switch.

Now for the more nuanced story:
For about a year now, all new accounts have been set up using ga.js instead of urchin.js. Here some of the benefits to using ga.js:

• Faster, smaller source file
• Automatic detection of HTTPS
• Increased namespace safety
• More convenient set up for tracking e-commerce transactions
• More customizable code for interactive Ajax-based sites
• Ability to take advantage of the most up-to-date tracking functionality as it is added to Google Analytics

Generally speaking, there are good reasons to make the switch and we certainly encourage people to do so. However, there is no immediate need or requirement to do so. Make the switch to ga.js when it is convenient for you or when you are ready to start taking advantage of the improved functionality.

Posted by Brett Crosby, Google Analytics Team