Who designed Word's "Mail Merge"? If you put n items on a page, with a <<Next Record>> tag after each one, you'll loose every n-th item. Apparently, there is an implicit <<Next Record>> at the end of the page.
The use a master-slave architecture, all writes go to the master datacenter in California. They modified MySQL replication so that they can invalidate datacenter-local memcache caches once the data gets replicated. And finally, they use a timestamped-cookie to solve the problem that read-after-write should see what you just wrote, even if you hit a data center that hasn't caught up on replication, yet.
- Sebastian Kanthak