To: Greg Smith <greg@2ndquadrant.com>
cc: Jason Tan Boon Teck <tanboonteck@gmail.com>, pgsql-admin@postgresql.org
Subject: Re: Downgrading v8.4 database to v8.3 
In-reply-to: <4BE1958F.8050708@2ndquadrant.com> 
References: <AANLkTinx2YotvMWtFTlB4-Hq57qoxguxgavbU6rpphNX@mail.gmail.com>
	<4BE1958F.8050708@2ndquadrant.com>
Comments: In-reply-to Greg Smith <greg@2ndquadrant.com>
	message dated "Wed, 05 May 2010 11:58:07 -0400"
Date: Wed, 05 May 2010 12:13:24 -0400
Message-ID: <3377.1273076004@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Greg Smith <greg@2ndquadrant.com> writes:
> Jason Tan Boon Teck wrote:
>> I need to move some databases written in Psql v8.4 to the stable
>> production server running v8.3. I tried pg_dump and pg_restore as well
>> as PgAdmin3.  I am unable to do so due to the backward
>> incompatibility. Is there anyway to do this?

> You can try connecting a 8.3 client to the 8.4 server, then running 
> pg_dump from that 8.3 client.  That's a  common approach for 
> dump/restore when moving forward a version, and it may resolve your 
> issue when moving backward one too.  The 8.3 client shouldn't dump 
> anything the 8.3 server doesn't know how to restore.

That's very likely to fail, and worse to do so silently, because 8.3
pg_dump doesn't know what's different about 8.4 system catalogs.

I think your only real recourse in this situation is to do a plain dump
from the 8.4 server (with 8.4 pg_dump) and then manually edit the dump
script to remove any 8.4-only syntax.  If your application isn't actually
using any 8.4-only features this should be a pretty trivial matter.
If it is, then of course you have some work to do.

			regards, tom lane