Re: Postgres Upgrade from 8.4 to 9.1

On 08/06/2012 01:38 PM, Rajiv Kasera wrote:
>
> Hi,
>
> I am planning a Postgres migration from 8.4 to 9.1 to be able to
> leverage the replication features available in the 9.1 version. I
> would like to understand the following things in this regard:
>
> 1.Any good documentation which should help in this upgrade.
>
The most important documentation here is the release notes for the major
.0 versions:

http://www.postgresql.org/docs/current/static/release-9-1.html
<http://www.postgresql.org/docs/9.1/static/release-9-1.html>
http://www.postgresql.org/docs/
<http://www.postgresql.org/docs/9.1/static/release-9-0.html>current
<http://www.postgresql.org/docs/9.1/static/release-9-1.html>/static/release-9-0.html
<http://www.postgresql.org/docs/9.1/static/release-9-0.html>

... in particular the "Migration to" sections.

> 2.To be able to replicate the complete steps in a test environment
> before doing it in LIVE which is running 9.0, is it possible to revert
> this database to 8.4 and then upgrade to 9.1.
>
No. Take a copy before upgrading. Always. Keep the copy read-only in
some safe place.

If you want to revert, make a copy of your backup and use that.

Upgrades from 8.4 to 9.0 or 9.1 require a dump and reload or the use of
the pg_upgrade tool. You can't just install the new version and start it
on your old database.

> 3.Any known issues and changes required to be done in the application
> for this upgrade.
>

See the release notes.

--
Craig Ringer