Re: Impossibly slow DELETEs

From: Stefan Champailler <schampailler(at)easynet(dot)be>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Impossibly slow DELETEs
Date: 2003-11-27 19:57:06
Message-ID: 200311272057.06718.schampailler@easynet.be
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I did not conduct much more test but from what I've seen, it looks like the
ODBC driver is in the doldrums, not PG. For example, when I run my software
on Windows rather than Linux, everything just works as expected. Sorry for
disturbing.

And btw, I use ODBC because my target DB is Oracle and I've been requested to
access it throguh ODBC. So, because I don't have Oracle, I do most of my
development with PG and then I'll port to Oracle. Since I'm doing "simple"
stuff, PG is almost 100% compatible with Oracle. (and before you ask, no,
they don't give me the proper dev environment, bastards :))

Thanks for all the answers.

Stefan

> Stefan Champailler wrote:
> > Dear You all,
> >
> > (please tell me if this has already been discussed, I was unable to find
> > any convincing information)
> >
> > I'm developing a small application, tied to a PG 7.4 beta 5 (i didn't
> > upgrade). The DB i use is roughly 20 tales each of them containing at
> > most 30 records (I'm still in development). I can provide a whole dump if
> > necessary. I access the DB throug IODBC (Suse Linux 8.1), through PHP.
> > The machine everything runs on is 512M of Ram, 2.5GHz speed. So I assume
> > it should be blazingly fast.
> >
> > So here's my trouble : some DELETE statement take up to 1 minute to
> > complete (but not always, sometimes it's fast, sometimes it's that slow).
> > Here's a typical one : DELETE FROM response_bool WHERE response_id =
> > '125' The response_bool table has no foreing key and no index on
> > response_id column. No foreign key reference the response_bool table.
> > There are 6 rows in the table (given that size, I assumed that an index
> > was not necessary).
> >
> > So 1 minute to complete look like I did something REALLY bad.
> >
> > It is my feeling that doing the same query with psql works without
> > problem, but I can't be sure.
>
> I think that last sentence is the crux of the problem. If you can
> establish for sure that the unreasonable delay is _only_ there when the
> command is issued through IODBC, then it's not a Postgresql problem.
>
> Out of curiosity, why are you using ODBC for PHP anyway? PHP has
> Postgresql libraries that work very well. I use them quite often without
> problems.

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