George Herbert wrote:
For the most part, web applications have a highly
effectively
paralleliseable app and web layer, but the database on many of them doesn't
scale horizontally as well.
Wikipedia can partition the database across languages (as it does
already with the largest ones), and when individual languages grow to be
too large for a single server to deal with, there are other partitioning
schemes to look at. So it's a bit simpler here, as it's not one
monolithic data store that's growing without bound.
Or for a counterexample, Friendster. I know the poor
guy who was doing site
architecture there for a while, screaming at his bosses that they needed to
get off MySQL and get a Sun/Oracle box in, and doing unholy things to MySQL
to try and keep it going, until he just walked away.
And yet an even larger social networking site continues to happily churn
along with MySQL. Clearly there are examples each way, but in the case
of WMF, there are also principles that factor into the equation.
--
Ivan Krstić <krstic(a)solarsail.hcs.harvard.edu> | GPG: 0x147C722D