I'm currently experimenting with the Debian packaging of 6.4.

The question arises of how to handle the change in library versions from
1.0 to 2.0.  It has been suggested that I should keep libpq.so.1 around
for the benefit of those who need to communicate with an older database
server.

Is it possible to use libpq.so.2.0 to query a remote database whose
server is running PostgreSQL 6.3?  What would be the consequences of
using libpq.so.1 to query a 6.4 server?

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
               PGP key from public servers; key ID 32B8FAA1
                 ========================================
     "Lo, children are an heritage of the LORD; and the  
      fruit of the womb is his reward."        Psalms 127:3 



Wed, 04 Nov 1998 00:09:21 +0000
"Oliver Elphick" <olly@lfix.co.uk>
Mixing library versions
On Wed, Nov 04, 1998 at 12:09:21AM +0000, Oliver Elphick wrote:
> I'm currently experimenting with the Debian packaging of 6.4.
> 
> The question arises of how to handle the change in library versions from
> 1.0 to 2.0.  It has been suggested that I should keep libpq.so.1 around
> for the benefit of those who need to communicate with an older database
> server.
> 
> Is it possible to use libpq.so.2.0 to query a remote database whose
> server is running PostgreSQL 6.3?  What would be the consequences of

No. Let's just try /usr/local/pgsql/bin/psql(6.4) on my running 6.3 server:

Connection to database 'mm' failed.
Unsupported frontend protocol.

> using libpq.so.1 to query a 6.4 server?

Never tried that until now. But it appears to work. I hvae no idea though
where it could break things.

Michael
-- 
Dr. Michael Meskes      | Th.-Heuss-Str. 61, D-41812 Erkelenz | Go SF49ers!
Senior-Consultant       | business: Michael.Meskes@mummert.de | Go Rhein Fire!
Mummert+Partner         |  private: Michael.Meskes@usa.net    | Use Debian
Unternehmensberatung AG |           Michael.Meskes@gmx.net    | GNU/Linux!

Wed, 4 Nov 1998 09:00:20 +0100
Michael Meskes <meskes@usa.net>
Re: [HACKERS] Mixing library versions
> On Wed, Nov 04, 1998 at 12:09:21AM +0000, Oliver Elphick wrote:
> > I'm currently experimenting with the Debian packaging of 6.4.
> > 
> > The question arises of how to handle the change in library versions from
> > 1.0 to 2.0.  It has been suggested that I should keep libpq.so.1 around
> > for the benefit of those who need to communicate with an older database
> > server.
> > 
> > Is it possible to use libpq.so.2.0 to query a remote database whose
> > server is running PostgreSQL 6.3?  What would be the consequences of
> 
> No. Let's just try /usr/local/pgsql/bin/psql(6.4) on my running 6.3 server:
> 
> Connection to database 'mm' failed.
> Unsupported frontend protocol.
> 
> > using libpq.so.1 to query a 6.4 server?
> 
> Never tried that until now. But it appears to work. I hvae no idea though
> where it could break things.

2.0 and 1.0 libpq can connect to 6.4, but 2.0 libpq can not connect to
older databases.  In other words, the backend can communicate with old
libpq, but old backends can not communicate with 2.0 libpq.

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Wed, 4 Nov 1998 09:04:31 -0500 (EST)
Bruce Momjian <maillist@candle.pha.pa.us>
Re: [HACKERS] Mixing library versions
"Oliver Elphick" <olly@lfix.co.uk> writes:
> Is it possible to use libpq.so.2.0 to query a remote database whose
> server is running PostgreSQL 6.3?

No.  That's why we changed the major version number, to make it
easier to keep an old libpq around if you need it.

> What would be the consequences of
> using libpq.so.1 to query a 6.4 server?

Should work fine.  The new server still handles the old FE/BE protocol.
(Or at least, it's supposed to ... I haven't tested that lately, but
I believe Tatsuo-san did.)

			regards, tom lane

Wed, 04 Nov 1998 10:00:03 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: [HACKERS] Mixing library versions 