>>> Alexander Staubo <alex@bengler.no> wrote:
> After upgrading from 8.2 to 8.3.5, the write load on our database
> server has increased dramatically and inexplicably -- as has the CPU
> usage.
Did you do a VACUUM ANALYZE of the database after loading it? Without
the database VACUUM, the first read of any page causes it to be
rewritten to set hint bits. Without an ANALYZE, it might be picking
very inefficient plans. I actually run a VACUUM FREEZE ANALYZE after
loading a database (as with the upgrade), to prevent massive rewrites
of everything in the database at some later date due to freeze
activity.
It could be something else, but I've seen similar behavior for the
above reasons.
-Kevin