[HyperDB] multi-datacenter configuration

[Andy Skelton]

> I¹ve read that wordpress.com has 3 data centers but I believe its only using
> master ­ slave replication.
> if this is the case, are you just using mysql replication to keep all dbs
> across data centers in sync?

That's right.

> And more specifically, how do you direct any writes (article posts or
> comments submitted) to the master db to do the write?

In the HyperDB config you specify the masters by setting their "write"
flag. See db-settings.php for details.

Andy