If you’re an engineer, you hate testing. Seriously, who likes doing what those mere mortal “users” do? We’re POWER users and we don’t need to use all those silly features on all those sites. Just look at Craigslist, clearly an engineer’s dream tool.
For web apps, testing actually isn’t *that* hard. The client program (the browser) is readily available on every platform known to man, and they generally don’t do much more than store and retrieve data in clever ways. So, its not like we have to fire up a Large Hadron Collider to observe the effects of our web app. Continue reading
There are quite a few articles out there that talk about how to give your application some context and send reads to one server, and writes to another. There are even some mentions of marking your connection “dirty” and then sending all reads to the write server.
As a first try at scaling things, I recently made a change to our web application’s data access layer where reads went to a group of readonly slaves. However, if a write was made to a database, a value was put into the user’s session, saying that the database was dirty, and causing all subsequent reads to go to the master server.