Peter Eisentraut <peter_e@gmx.net> writes:
> Trond Eivind Glomsrød writes:
>
> > > %preupgrade
> > > pg_dumpall >somewhere
>
> > 1) You don't know that postgresql is running. It probably isn't.
>
> Then start it.
That may not be possible, and wouldn't handle the possibility of it
not starting.
> > 2) You don't know that you have the diskspace to do that.
>
> Changing from one storage format to another always requires 2x space
> (although a text dump is usually smaller than the internal
> representation).
That depends on how you manipulate the on-disk format, but right now,
a problem is you have to do this before upgrading. Having a separate
tool going from one on-disk format to another and possibly failing
because of lack of disk space is OK - as long you can run it later
when you've added more space or point at a place with enough space
etc.
> And you're not going to get the storage format to not
> ever change again. :-)
With some thought and design for adding future capabities, perhaps it
could be possible?
--
Trond Eivind Glomsrød
Red Hat, Inc.