From: Tom Lane <tgl@sss.pgh.pa.us>
To: Scott Beil <SBeil@800link.com>
cc: pgsql-interfaces@postgresql.org
Subject: Re: Sporadic "relation does not exist" errors with psqlODBC
In-reply-to: <1136454500-180960@mail.800link.com>
References: <1136454500-180960@mail.800link.com>
Comments: In-reply-to Scott Beil <SBeil@800link.com>
	message dated "Tue, 11 Jul 2017 19:29:47 -0500"
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Date: Wed, 12 Jul 2017 11:53:15 -0400
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Scott Beil <SBeil@800link.com> writes:
> Every once in a while I get this error:
> ERROR: column "column_name" of relation "table_name" does not exist

> - The problem only occurs when under load.=C2=A0
> - The database version is=C2=A09.6.3
> - The problem exists in ODBC versions=C2=A009.03.0300 and=C2=A009.06.0310=
, but not in=C2=A009.00.0310 (versions not mentioned have not been tested)
> - Two identical applications are running simultaneously. One uses 09.06.0=
310, the other uses 09.00.0310. The one using 09.06.0310 exhibits the error=
, the one using 09.00.0310 does not. By the way, the app using 09.00.0310 t=
hat does not produce the error is typically under a heavier load than the o=
ne that does.
> - The column name in the error is one I recognize, but it belongs to anot=
her table than the one reported in the error.
> - To the best of my knowledge, only inserts and updates are affected.

It seems unlikely to me that the ODBC version has much to do with this.
I can imagine server bugs that would cause it ... but actually finding
such a bug, if it exists, is harder.

Have you checked that the statements suffering the error are sane (that
is, they actually name valid table/column combinations)?  Is there any
other commonality in the statements suffering the error?  Can you
correlate occurrences of the error with DDL being executed in other
sessions?

> Of course the big problem here is how to reproduce or capture the problem=
 in a log when it is sporadic and only occurs under load. I would like to s=
ee this problem resolved and am willing to do my part.

What I'd think about is trying to boil down/sanitize your workload into
something you can submit as a self-contained test case.  If you can do
anything that increases the frequency of the error, better yet.

			regards, tom lane


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