Re: What does Page Layout version mean? (Was: Re: Reducing NUMERIC size for 8.3)

Andrew Sullivan wrote:
> On Wed, Jun 20, 2007 at 12:34:21PM -0400, Robert Treat wrote:
>> FWIW pg_migrator is a pretty good swing at an in-place upgrade tool for
>> 8.1->8.2. Unfortunately until the PGDG decides that in-place upgrade is a
>> constraint their willing to place on development, I see them a good
>> chicken/egg away from making it a continually usefull tool.
>
> Or maybe cart/horse. It seems to me that the rule more likely needs
> to be that the migrator follow the development of the database than
> that the database engine be strongly constrained by the needs of an
> upgrade tool. I agree that some commitment is needed, though.

I don't think that upgrade will strongly constrain a database engine.
But some constrains we can expect. Any new development in some area will
have to take care about upgrade. If you break some "upgrade coding
rules" you will not to able create upgrade procedure or upgrade process
will be risky.

For example upgrade between 8.1 -> 8.2 is risky, because you are not
able easy determine what format of cidr/inet is used on the page. If
something fails during table structure upgrade, then it is not easy to
recovery from this situation.

Zdenek