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

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Jim Nasby <jim(at)nasby(dot)net>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Daniel Farina <daniel(at)heroku(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Removing freelist (was Re: Should I implement DROP INDEX CONCURRENTLY?)
Date: 2012-01-23 02:06:39
Message-ID: CA+TgmoaOFLiAf8wEqJKv7xvf+TdybJ4wCkQxkO95uXtJ=yc8Bw@mail.gmail.com
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On Sat, Jan 21, 2012 at 5:29 PM, Jim Nasby <jim(at)nasby(dot)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 (!). So I guess
my vote would be to leave it alone pending further study, and maybe
remove it later if we can't find a way to rejigger it to be more
useful.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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