From: Bruce Momjian <bruce@momjian.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Florian Weimer <fweimer@bfk.de>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Large number of open(2) calls with bulk INSERT into empty table
Date: Thu, 16 Aug 2012 21:05:24 -0400
Message-ID: <20120817010524.GL30286@momjian.us> (raw)
In-Reply-To: <CA+TgmobRiGQH+GNC+vTmEf=AgknBirSEUy3PFg4MzpXTXmfLqQ@mail.gmail.com>
References: <82ipm51tcd.fsf@mid.bfk.de>
<CA+TgmoYRGO5Wu4_2yzP0-cmx4GBZHqOO4WKiCxT-R3gV6qrt6A@mail.gmail.com>
<827h29q4pd.fsf@mid.bfk.de>
<CA+TgmobRiGQH+GNC+vTmEf=AgknBirSEUy3PFg4MzpXTXmfLqQ@mail.gmail.com>
A TODO for this?
---------------------------------------------------------------------------
On Tue, Dec 6, 2011 at 02:53:42PM -0500, Robert Haas wrote:
> On Tue, Dec 6, 2011 at 7:12 AM, Florian Weimer <fweimer@bfk.de> wrote:
> > * Robert Haas:
> >
> >> I tried whacking out the call to GetPageWithFreeSpace() in
> >> RelationGetBufferForTuple(), and also with the unpatched code, but the
> >> run-to-run randomness was way more than any difference the change
> >> made. Is there a better test case?
> >
> > I think that if you want to exercise file system lookup performance, you
> > need a larger directory, which presumably means a large number of
> > tables.
>
> OK. I created 100,000 dummy tables, 10,000 at a time avoid blowing up
> the lock manager. I then repeated my previous tests, and I still
> can't see any meaningful difference (on my MacBook Pro, running MacOS
> X v10.6.8). So at least on this OS, it doesn't seem to matter much.
> I'm inclined to defer putting any more work into it until such time as
> someone can demonstrate that it actually causes a problem and provides
> a reproducible test case. I don't deny that there's probably an
> effect and it would be nice to improve this, but it doesn't seem worth
> spending a lot of time on until we can find a case where the effect is
> measurable.
>
> On the other hand, the problem of the FSM taking up 24kB for an 8kB
> table seems clearly worth fixing, but I don't think I have the cycles
> for it at present. Maybe a TODO is in order.
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>
> --
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--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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To: pgsql-hackers@postgresql.org
Cc: bruce@momjian.us, robertmhaas@gmail.com, fweimer@bfk.de
Subject: Re: Large number of open(2) calls with bulk INSERT into empty table
In-Reply-To: <20120817010524.GL30286@momjian.us>
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