Message-Id: <3597E0BB.DA0DF3DA@insightdist.com>
Date: Mon, 29 Jun 1998 14:45:16 -0400
From: David Hartwig <daveh@insightdist.com>
Organization: Insight Distribution Systems
Mime-Version: 1.0
To: Christian Steindl <e9425178@student.tuwien.ac.at>
Cc: pgsql-interfaces@postgreSQL.org
Subject: Re: [INTERFACES] scrollable cursor via odbc
References: <Pine.A41.3.95.980629182008.74084A-100000@stud1.tuwien.ac.at>
Content-Type: text/plain; charset=us-ascii
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Christian,

The problem is in the backend optimizer.   If you turn on the commlog, you
will find that queries are being generated with lots of ORs.  This is to get
a record set.   If you run that query with EXPLAIN you will find that it is
doing a sequential scan. (Maybe several per  page scroll.)  Even worse, if
you have a multi-part key, the optimizer will spend (expend) much resource
CNFifying the where clause.

I am working on a patch to resolve this in the backend.   I have a workable
solution, for queries with this particular signature,  but I am trying to
make it more general purpose in nature.

Christian Steindl wrote:

> i use the odbc interface to the postgresql but it seems to be quite
> slowly.
> although it's a single table with about 20.000 rows.
> i set a link in an access-db and scrolling (next page, last row) is very
> slowly.
> is there a way to optimize the performance?
> can i use scrollable cursor via the odbc-drv?
>
> best regards
>