Date: Sun, 22 Jun 2003 20:07:02 -0700
From: Sean Chittenden <sean@chittenden.org>
To: nolan@celery.tssi.com
Cc: Jan Wieck <JanWieck@Yahoo.com>, Bruce Momjian <pgman@candle.pha.pa.us>,
	Josh Berkus <josh@agliodbs.com>, Joe Conway <mail@joeconway.com>,
	"\"Advocacy PostgreSQL\"" <pgsql-advocacy@postgresql.org>,
	PostgreSQL-general <pgsql-general@postgresql.org>
Subject: Re: [GENERAL] interesting PHP/MySQL thread
Message-ID: <20030623030702.GM97131@perrin.int.nxad.com>
References: <3EF655E7.9070709@Yahoo.com>
	<20030623025439.28324.qmail@celery.tssi.com>
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> I know it took me a while to convince the CIO on the project I'm working
> on that PostgreSQL was an improvement over MySQL.  He's slowly coming
> around as I start to show him what I am doing with the much richer 
> PostgreSQL feature set, but the performance of 7.3 compared to MySQL is 
> likely to remain a bit of a sticking point, because some queries are 
> taking 2-3 times as long on the same platform with the same data.
> 
> If the data entry folks, who are probably about to get a look at a portion 
> of the application that is still using the MySQL engine, get used to the 
> search times there, when we switch the whole thing over to PostgreSQL we 
> may get complaints if searches that used to take 3-4 seconds are now 
> taking 10-12 seconds.  (Have others noticed that 7 seconds seems to be 
> a threshold point for users reacting to query times?)

Whoa, something's not right.  Could you please send along an EXPLAIN
ANALYZE after doing a VACUUM ANALYZE of your query that's taking 3-4x
longer?  Something smells very strange here because my experience has
been quite the opposite...  I can understand 0.05ms longer per
connection in setup overhead (fork() vs new thread) , but this seems
like way too much... I wonder if you couldn't benefit from the use of
a cursor if you're returning a large dataset.  -sc

http://developer.postgresql.org/docs/postgres/sql-declare.html
http://developer.postgresql.org/docs/postgres/sql-fetch.html
http://developer.postgresql.org/docs/postgres/sql-close.html

-- 
Sean Chittenden