Re: Write ahead logging

From: Matthias Meixner <meixner(at)dvs1(dot)informatik(dot)tu-darmstadt(dot)de>
To: Rod Taylor <rbt(at)rbt(dot)ca>
Cc: Mario Weilguni <mweilguni(at)sime(dot)com>, Manfred Koizar <mkoi-pg(at)aon(dot)at>, Postgresql Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Write ahead logging
Date: 2003-03-07 08:44:22
Message-ID: 3E685BE6.4090008@dvs1.informatik.tu-darmstadt.de
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Rod Taylor wrote:
> What were you using to measure the latency. Don't suppose you could
> send it over. The admins locally don't like what I used to do the test
> with -- they don't want to turn off write-caching for other reasons.

I am doing an insert of few bytes, so that the amount of data does not
significantly affect the measured time. And for measuring time without
cache, I temporarily switched it off.

That was the code used (nothing unusual):

#include "timeval.h"

main()
{
Timeval start,end;
EXEC SQL WHENEVER sqlerror sqlprint;
EXEC SQL WHENEVER not found sqlprint;

EXEC SQL CONNECT TO user(at)localhost;
start=Timeval::Time();
EXEC SQL BEGIN;
EXEC SQL INSERT INTO test values ('qwertz');
EXEC SQL COMMIT;
end=Timeval::Time();
end-=start;
printf("time: %d.%06d\n",end.tv_sec,end.tv_usec);
}

- Matthias Meixner

--
Matthias Meixner meixner(at)informatik(dot)tu-darmstadt(dot)de
Technische Universität Darmstadt
Datenbanken und Verteilte Systeme Telefon (+49) 6151 16 6232
Wilhelminenstraße 7, D-64283 Darmstadt, Germany Fax (+49) 6151 16 6229

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