From: Tom Lane <tgl@sss.pgh.pa.us>
To: Sebastien FLAESCH <sf@4js.com>
cc: hlinnaka@iki.fi, pgsql-docs@postgresql.org
Subject: Re: Details about libpq cross-version compatibility
In-reply-to: <50518F47.30806@4js.com>
References: <5050A86B.4080601@4js.com> <505184B6.6050008@iki.fi>
	<50518F47.30806@4js.com>
Comments: In-reply-to Sebastien FLAESCH <sf@4js.com>
	message dated "Thu, 13 Sep 2012 09:46:15 +0200"
Date: Thu, 13 Sep 2012 18:25:07 -0400
Message-ID: <23464.1347575107@sss.pgh.pa.us>

Sebastien FLAESCH <sf@4js.com> writes:
> If a future major version (for ex 9.3) implements a new strategic feature
> that makes libpq headers incompatible with prior versions, what shall we
> do with our convention? Shall we ship 9.x (where 0<=x<=2) drivers and 9.3+
> drivers? What if a next major version implements again another feature
> that makes headers incompatible again?

We've never done that AFAIR.  When and if it happens, that would be the
time to deal with it.

> I think I am asking for is an official statement that clearly says that
> libpq headers are only compatible for a given set of minor versions, like
> (8.4.1, 8.4.2, 8.4.3, ...) or (9.2.1, 9.2.2, ...)

> I believe also that the libpq library should automatically check for
> compatiblity, based on PG_MAJORVERSION definition in pg_config.h ...

It seems highly undesirable to me that we should intentionally break
cross-version compatibility, which is what you seem to be proposing.

			regards, tom lane