Re: UPDATE slow

John Smith  writes:
> Here are my postgresql.conf settings (I just uncommented the mentioned vars and restarted):

> shared_buffers = 64  # 2*max_connections, min 16, typically 8KB each

There's your problem, or part of it anyway.  That's not enough buffers
to manipulate a bunch of indexes efficiently.  Production-grade settings
for shared_buffers are more like 1 to 10 thousand.

> max_fsm_relations = 100 # min 10, fsm is free space map, ~40 bytes
> max_fsm_pages = 10000  # min 1000, fsm is free space map, ~6 bytes

You probably will want to jack those up too.

> sort_mem = 1024  # min 64, size in KB

And possibly that, though I don't think it affects this particular
query.

			regards, tom lane