Обсуждение: Mixing library versions

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
ID32B8FAA1                ========================================    "Lo, children are an heritage of the LORD; and
the      fruit of the womb is his reward."        Psalms 127:3 
 

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!

> 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,
Pennsylvania19026
 

"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