Compatibility between different versions of psql client and postgresql server

[Cris Carampa]

When connecting from a psql client version xyz to a postgresql server
version zyx across the network, what are the rules to follow for
assuring compatibility between different versions?

For example, is it possible to connect from psql 7.2.x to postgresql
server 7.4.x?

Thank you. Kind regards,

[Greg Sabino Mullane]

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Post by Cris Carampa
When connecting from a psql client version xyz to a postgresql server
version zyx across the network, what are the rules to follow for
assuring compatibility between different versions?

The basic rule is: use the same version for both.

Post by Cris Carampa
For example, is it possible to connect from psql 7.2.x to postgresql
server 7.4.x?

This one is possible, but anytime you mix versions, you will probably have
problems. Since psql is part of the main PostgreSQL distribution, if
you have the 7.4.x server, you should have the 7.4.x psql as well. 7.2.x
(the server) is rather old and has some serious issues, and it should not
be used. In general, going from an older psql to a newer server will cause
less problems than going the other way.

Having said all of that, there is an effort underway to try and
make psql a little more forgiving. The 8.0 version can work against 7.4
servers, and I'm going to try and keep things relatively portable as we
move forward from 8.0. However, it will never work against 7.2 servers
(too many changes from 7.2->7.3 to make it worth the trouble) and *may*
at some point read 7.3 servers, but that gets less likely as time moves on.

- --
Greg Sabino Mullane ***@turnstep.com
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[Tom Lane]

Post by Cris Carampa
When connecting from a psql client version xyz to a postgresql server
version zyx across the network, what are the rules to follow for
assuring compatibility between different versions?

[snip]
... In general, going from an older psql to a newer server will cause
less problems than going the other way.

One other point is that just connecting and issuing SQL queries should
work, more or less independently of which psql and backend mix you're
using. What is likely to fail is psql's backslash commands, because
those have hard-wired knowledge about the system catalogs, which change
from version to version.

regards, tom lane

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