Message-ID: <3778F732.6C2A0D5D@solipsys.com>
Date: Tue, 29 Jun 1999 12:41:23 -0400
From: Byron Nikolaidis <byronn@solipsys.com>
MIME-Version: 1.0
To: Dave Page <dpage@vale-housing.co.uk>
CC: "'pgsql-interfaces@postgresql.org'" <pgsql-interfaces@postgreSQL.org>
Subject: Re: [INTERFACES] ODBC: OID column in views
References: <B9FE686F5C26D311AC22006097BCD3D65EFE@woody.vale-housing.co.uk>
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Dave Page wrote:

> >
> > I'm not sure what you mean by "the driver will always attempt
> > to retrieve the oid
> > column"...  What is the driver doing?  If it is sending
> > another query, could you show
> > me exactly what because its been a while since I looked at the code.
>
> The commlog shows the following when the query 'SELECT * FROM pg_tables;' is
> executed via DAO (I've just thought though, would it be the driver or
> perhaps DAO that is expanding the wildcard?):
>
> conn=175915324, query='SELECT "oid" ,"tablename" ,"tableowner" ,"hasindexes"
> ,"hasrules" ,"hastriggers"  FROM "pg_tables" '
> ERROR from backend during send_query: 'ERROR:  system column oid not
> available - pg_tables is a view'
> STATEMENT ERROR: func=SC_execute, desc='', errnum=1, errmsg='Error while
> executing the query'
>
> Presumably if it's DAO that's expanding the wildcard, it would still be the
> driver reporting the existance of the oid column?
>

Ahhhh,  I see now.  DAO is calling SQLColumns() on the "pg_tables" table.  Since
the driver realizes it is a system table (i.e., because it begins with pg_), it
automatically throws the OID column in there.  There is no option to turn that
off and it is not intelligent enough to check whether it is a view.

The idea was that when looking at System Tables, you would always be interested
in the oid column so the driver should show it.

Wait a minute, I don't remember any "pg_tables" view???  Is that really a system
table, or something you created?  If its something you created, you can just not
start it with "pg_" and problem solved!

Another possibility is to use SQLTables() meta function to get the tables
instead of using a low level query.  Theoretically, it would be more portable.

Byron