Subject: Re: [SQL] EXTERNAL storage and substring on long strings
From: Scott Cain <cain@cshl.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PgSQL Performance ML <pgsql-performance@postgresql.org>,
	pgsql-sql@postgresql.org
In-Reply-To: <3574.1060012423@sss.pgh.pa.us>
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Organization: Cold Spring Harbor Lab
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Date: 04 Aug 2003 12:25:41 -0400
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On Mon, 2003-08-04 at 11:53, Tom Lane wrote:
> Scott Cain <cain@cshl.org> writes:
> > At least this appears to work and is much faster, completing substring
> > operations like above in about 0.27 secs (that's about two orders of
> > magnitude improvement!)
> 
> I find it really, really hard to believe that a crude reimplementation
> in plpgsql of the TOAST concept could beat the built-in implementation
> at all, let alone beat it by two orders of magnitude.
> 
> Either there's something unrealistic about your testing of the
> dna_string function, or your original tests are not causing TOAST to be
> invoked in the expected way, or there's a bug we need to fix.  I'd
> really like to see some profiling of the poor-performing
> external-storage case, so we can figure out what's going on.
> 
I was really hoping for a "Good job and glad to hear it" from you :-)

I don't think there is anything unrealistic about my function or its
testing, as it is very much along the lines of the types of things we do
now.  I will really try to do some profiling this week to help figure
out what is going on.

Scott

-- 
------------------------------------------------------------------------
Scott Cain, Ph. D.                                         cain@cshl.org
GMOD Coordinator (http://www.gmod.org/)                     216-392-3087
Cold Spring Harbor Laboratory