From: Bruce Momjian <maillist@candle.pha.pa.us>
Message-Id: <199807231945.PAA13730@candle.pha.pa.us>
Subject: Re: [HACKERS] ODBC and palloc ...
In-Reply-To: <35B77342.6558C42B@insightdist.com> from Byron Nikolaidis at "Jul
	23, 1998  1:30:42 pm"
To: byronn@insightdist.com (Byron Nikolaidis)
Date: Thu, 23 Jul 1998 15:45:04 -0400 (EDT)
Cc: dlibenzi@maticad.it, pgsql-hackers@postgreSQL.org,
	pgsql-interfaces@postgreSQL.org, daveh@insightdist.com
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> Davide Libenzi wrote:
> > 
> > After a lot of changes I've compiled,linked and tested (regression) my
> > PostgreSQL installation no HPUX 9.*.
> > 
> > I've also built and installed the ODBC driver and I get Ms Access error
> > which the PostgresSQL server log in "palloc failure : memory exausted".
> > 
> > Is this a server bug or ODBC driver bug ?
> > 
> 
> I am assuming you have a fairly new odbc driver (6.30.0248 is the
> latest) and not the old postodbc.  BTW, on our website
> (www.insightdist.com/psqlodbc) we have the DLL and a full install EXE
> for win32 so you wouldn't have to build it yourself from the source code
> if you didn't want to.
> 
> The palloc failure usually occurs because Access uses the multiple OR
> query (select ... where a=1 OR a=2 OR a=3...) to access the recordset.
> The backend does not handle this very well and it is already well known
> on the TODO list.
> 
> There are several possibilities to get past this:
> 1. Use a non-updateable table (by setting the driver readonly option, or
> by not specifying any unique identifiers).
> 2. For a query, use a snapshot recordset in the query properties.
> 3. Show the OID column in the drivers advanced datasource options and
> use that alone to index on.  You should create an index on it too.  This
> is still slow, but at least shouldn't crash.
> 
> Other possibilities:
> 
> In house, Dave made a patch to postgres which rewrites the multiple OR
> query into a UNION query, which works great and its fast!  We may make
> this patch available evntually on our website.

I am thinking about this right now, and will post an analysis within the
next day.

-- 
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