Re: version upgrade

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 ...
>
> ----
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> (http://www.hub.org)
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Andrew Rawnsley
President
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(740) 587-0114
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