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
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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.

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"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