Sender: emarsden@rossini.laas.fr
To: pgsql-interfaces@postgreSQL.org
Subject: OIDs in pg_type stable across versions?
Organization: LAAS-CNRS  http://www.laas.fr/
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
From: Eric Marsden <emarsden@mail.dotcom.fr>
Date: 20 Jan 1999 11:16:31 +0100
Message-ID: <wzi3e56ckqo.fsf@mail.dotcom.fr>
Lines: 26

Hello,

I have written a socket-level interface to PostgreSQL for scsh, an
implementation of the Scheme programming language which provides a
POSIX interface. Unlike Tcl or Perl, Scheme distinguishes between
numbers and strings and booleans and so on (it's a real programming
language :), so I'm looking at how it might be possible to convert
data retrieved from the backend as a character stream into the
appropriate Scheme types.

The fe-be protocol seems to provide sufficient information to do this
type coercion: when the backend sends the attribute data in response
to a SELECT statement, it sends a sequence of tuples (name, type-id,
size). The type-id is an OID from the pg_type table.

Is is reasonable to assume that these oids will be stable across
versions and platforms, or will I have to reconstruct a table from
a `SELECT typname, oid FROM pg_type' each time a connection is
initiated? 

(or maybe there's some simpler way to do the type coercions?)

-- 
Eric Marsden
emarsden @ mail.dotcom.fr
It's elephants all the way down