From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200602111501.k1BF1i017587@candle.pha.pa.us>
Subject: Re: Finding the pqlib version
In-Reply-To: <43EDC399.6060203@online.de>
To: Christoph Zwerschke <cito@online.de>
Date: Sat, 11 Feb 2006 10:01:44 -0500 (EST)
CC: pgsql-interfaces@postgresql.org
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Christoph Zwerschke wrote:
> I want to add the PQCancel() functionality to PyGreSQL.
> Until now, PyGreSQL works with PostgreSQL 7.3+, but
> unfortunately, PQCancel() is only available from 8.0+.
> 
> In order to not break compilation of PyGreSQL on systems with PG7,
> I would like to do something like the following:
> 
> #if PQLIB_VERSION_MAJOR < 8
>    PQRequestCancel(conn)
> #else
>    c = PQgetCancel(conn)
>    PQCancel(c, errbuf, 256)
>    PQfreeCancel(c)
> #end
> 
> However, there is no such thing as "PQLIB_VERSION_MAJOR".
> Anything else I could query instead?

You want the server version.  In PostgreSQL 8.0 and later you can use
libpq's PQserverVersion(), but for pre-8.0, I think you have to do
SELECT version(), and parse that:

	test=> SELECT version();
	                             version
	------------------------------------------------------------------
	 PostgreSQL 8.2devel on i386-pc-bsdi4.3.1, compiled by GCC 2.95.3
	(1 row)

I would also look how other interfaces are doing this.

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