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Subject: Re: [PATCHES] [SQL] 16 parameter limit
From: Hannu Krosing <hannu@tm.ee>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter_e@gmx.net>,
	Neil Conway <nconway@klamath.dyndns.org>,
	Christopher Kings-Lynne <chriskl@familyhealth.com.au>,
	Bruce Momjian <pgman@candle.pha.pa.us>, josh@agliodbs.com,
	jproctor@prium.net, PostgreSQL Development <pgsql-hackers@postgresql.org>
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Date: 16 Apr 2002 21:12:52 +0200
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On Tue, 2002-04-16 at 07:01, Tom Lane wrote:
> Peter Eisentraut <peter_e@gmx.net> writes:
> > How about this:  We store the first 16 parameters in some fixed array for
> > fast access like now, and when you have more than 16 then 17 and beyond
> > get stored in some variable array in pg_proc.
> 
> <<itch>>  What's this going to cost us in the function lookup code paths?
> 
> If we can do it with little or no performance cost (at least for the
> "normal case" of fewer-than-N parameters) then I'm all ears.

Perhaps we could use the 16-th element as an indicator of 16-or-more
args. If it is 0 then there are <= 15 args if it is something else, then
this something else is hash of extra argument types that need to be
looked up separately. 

Of course we will need some way of resolving multiple hash matches.

--------------
Hannu