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Re: Inlining comparators as a performance optimisation

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andrew Dunstan <andrew(at)dunslane(dot)net>, Peter Geoghegan <peter(at)2ndquadrant(dot)com>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Inlining comparators as a performance optimisation
Date: 2011-09-21 16:13:20
Message-ID: 4E7A0D20.1060709@enterprisedb.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On 21.09.2011 18:46, Tom Lane wrote:
> Well, we'd have to negotiate what the API ought to be.  What I'm
> envisioning is that datatypes could provide alternate comparison
> functions that are designed to be qsort-callable rather than
> SQL-callable.  As such, they could not have entries in pg_proc, so
> it seems like there's no ready way to represent them in the catalogs.

Quite aside from this qsort-thing, it would be nice to have versions of 
all simple functions that could be called without the FunctionCall 
overhead. So instead of:

FunctionCall2(&flinfo_for_int4pl, 1, 2)

you could do simply

int4pl_fastpath(1,2)

I'm not sure how big an effect this would have, but it seems like it 
could shave some cycles across the system.

We could have an extended version of the PG_FUNCTION_INFO_V1 macro that 
would let you register the fastpath function:

PG_FUNCTION_INFO_V1(int4pl, int4pl_fastpath);

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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Subject: DECLARE CURSOR must not contain data-modifying statements in WITH
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