Horton

Re: Removing freelist (was Re: Should I implement DROP INDEX CONCURRENTLY?)

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Jim Nasby <jim@nasby.net>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Simon Riggs <simon@2ndquadrant.com>, Daniel Farina <daniel@heroku.com>, Merlin Moncure <mmoncure@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2012-01-23T05:12:48Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Sat, Jan 21, 2012 at 5:29 PM, Jim Nasby <jim@nasby.net> wrote:
>> We should also look at having the freelist do something useful, instead of just dropping it completely. Unfortunately that's probably more work...

> That's kinda my feeling as well.  The free list in its current form is
> pretty much useless, but I don't think we'll save much by getting rid
> of it, because that's just a single test.  The expensive part of what
> we do while holding BufFreelistLock is, I think, iterating through
> buffers taking and releasing a spinlock on each one (!).

Yeah ... spinlocks that, by definition, will be uncontested.  So I think
it would be advisable to prove rather than just assume that that's a
problem.

			regards, tom lane