Re: Large number of open(2) calls with bulk INSERT into empty table

A TODO for this?

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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(at)bfk(dot)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(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +