Re: version upgrade - Mailing list pgsql-hackers

On Aug 31, 2004, at 6:23 PM, Marc G. Fournier wrote:

> On Tue, 31 Aug 2004, Josh Berkus wrote:
>
>> Andrew,
>>
>>> If I were loony enough to want to make an attempt at a version 
>>> updater
>>> (i.e. migrate a
>>> 7.4 database to 8.0 without an initdb), any suggestions on where to
>>> poke first? Does a
>>> catalog/list of system catalog changes exist anywhere? Any really 
>>> gross
>>> problems immediately
>>> present themselves? Is dusting off pg_upgrade a good place to start, 
>>> or
>>> is that a dead end?
>>
>> Join the Slony project?    Seriously, this is one of the uses of 
>> slony.  All
>> you'd need would be a script that would:
>>

I thought of this quite a bit when I was working over eRServer a while 
back.

Its _better_ than a dump and restore, since you can keep the master up 
while the
'upgrade' is happening.  But Mark is right - it can be quite 
problematic from an equivalent
resource point of view. An in-place system (even a faux setup like 
pg_upgrade) would be
easier to deal with in many situations.

In the end, using a replication system OR a working pg_upgrade is still 
a pretty creaky
workaround. Having to do either tends to lob about 15 pounds of nails 
into the gears when
trying to develop a business case about upgrading (Doesn't necessarily 
stop it dead, but
does get everyone's attention...). The day when a dump/restore is not 
necessary is
the day all of us are hoping for.


>> 1) Install PG 8.0 to an alternate directory;
>> 2) Start 8.0;
>> 3) install Slony on both instances (the 7.4 and the 8.0);
>> 4) make 7.4 the "master" and start replicating
>> 5) when 8.0 is caught up, stop 7.4 and promote it to Master
>> 6) turn off Slony.
>
> Slony is not an upgrade utility, and falls short in one big case .. 
> literally .. a very large database with limited cash resources to 
> duplicate it (as far as hardware is concerned).  In small shops, or 
> those with 'free budget', Slony is perfect ... but if you are in an 
> organization where getting money is like pulling teeth, picking up a 
> new server "just to do an upgrade" can prove to be difficult ...
>
> ----
> Marc G. Fournier           Hub.Org Networking Services 
> (http://www.hub.org)
> Email: scrappy@hub.org           Yahoo!: yscrappy              ICQ: 
> 7615664
>
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Andrew Rawnsley
President
The Ravensfield Digital Resource Group, Ltd.
(740) 587-0114
www.ravensfield.com