Re: Database is slow, vacuum hangs

"Nick Fankhauser" <nickf@ontko.com> writes:
> The deletes were slow, but worked, so the tables are all empty now. I
> started the vacuum and let it run for 4 hours while I did other work & it
> never came back.

Is the vacuum actually running (accumulating any CPU time)?  Or is it
just waiting on a lock held by one of those other guys?

> During this time, I noticed that two postmaster processes
> were constantly running- each taking up almost exactly half of the CPU time.
> There was no disk activity. After I canceled the vacuum, the two postmaster
> processes remained and continued to use all of the CPU time. (they're still
> there.)

And what are they doing --- who started them, what query was sent to
'em, etc?

If you haven't a clue, try attaching to each process with a debugger and
printing out the global variable debug_query_string.

            regards, tom lane