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Re: Trigger performance

From: Pavel Stehule <stehule(at)kix(dot)fsv(dot)cvut(dot)cz>
To: pginfo <pginfo(at)t1(dot)unisoftbg(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Trigger performance
Date: 2004-01-23 07:35:27
Message-ID: Pine.LNX.4.44.0401230834030.10349-100000@kix.fsv.cvut.cz (view raw or flat)
Thread:
Lists: pgsql-performance
Hello

try prepared statements, PQexecPrepared
http://developer.postgresql.org/docs/postgres/libpq-exec.html

Regards
Pavel Stehule

On Thu, 22 Jan 2004, pginfo wrote:

> Hi,
> 
> thanks for the answer.
> It is very interest, because I readet many times that if I write the trigger
> in "C" it will work faster.
> In wich case will this trigger work faster if write it in "C"?
> In all my triggres I have "select ...." or "insert into mytable select ..."
> or "update mytable set ...where...".
> I need this info because I have a table with ~1.5 M rows and if I start to
> update 300 K from this rows it takes ~ 2h.
> If I remove the trigger for this table all the time is ~ 1 min.
> 
> regards,
> ivan.
> 
> Tom Lane wrote:
> 
> > pginfo <pginfo(at)t1(dot)unisoftbg(dot)com> writes:
> > > I was supprised that the pgsql trigger take ~8 sec. to insert this rows
> > > and the "C" trigger take ~ 17 sec.
> >
> > The reason is that plpgsql caches the plan for the invoked SELECT,
> > whereas the way you coded the C function, it's re-planning that SELECT
> > on every call.
> >
> >                         regards, tom lane
> >
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> 
> 
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