Re: [HACKERS] Re: TODO updates

The Hermit Hacker <scrappy@hub.org> writes:
>>>> removal of the whole pg_vlock requirement on vacuum?
>> 
>> I have that on my to-do list; as far as I know it's a trivial code
>> change, but I just haven't gotten to it.  Maybe I'll try it tonight.

> is this something that could safely be back-patched into v6.5.x's tree?

Well, mumble.  We could probably back-patch the ability to run more than
one vacuum at a time, since that'd be local to vacuum.c.  But I think
that'd encourage people to run vacuum in parallel with *other* database
activities, something we know is not very safe in 6.5!  That whole
set of changes I made to enforce more careful locking was mainly
motivated by Oleg's examples of crashes when system table changes were
made in parallel with vacuuming of the system tables.

In short, I think it'd be a risky thing to do.  I'm not even 100%
confident that it will work reliably in current sources; I'll check
it out before I commit it, but I won't be really comfortable until
we've had a beta-test cycle on it...
        regards, tom lane