Re: Postgres Upgrade from 8.4 to 9.1

Craig Ringer <ringerc@xxxxxxxxxxxxx> · Wed, 08 Aug 2012 14:50:26 +0800



    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/current/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