Re: pg_migrator issues - Mailing list pgsql-hackers

Robert Haas wrote:
> On Mon, Jan 4, 2010 at 2:52 PM, Bruce Momjian <bruce@momjian.us> wrote:
> > Robert Haas wrote:
> >> On Mon, Jan 4, 2010 at 2:11 PM, Bruce Momjian <bruce@momjian.us> wrote:
> >> > Alvaro Herrera wrote:
> >> >> > 2) ?Right now pg_migrator renames old tablespaces to .old, which fails
> >> >> > if the tablespaces are on mount points. ?I have already received a
> >> >> > report of such a failure.
> >> >>
> >> >> I thought it was impossible to use bare mountpoints as tablespaces due
> >> >> to ownership problems ... Is that not the case? ?-1 for special hacks
> >> >> that work around bogus setups, if that means intrusive changes to the
> >> >> core code.
> >> >
> >> > I talked to the person who reported the problem and he and I confirmed
> >> > that it is quite easy to make the mount point be owned by the postgres
> >> > user and have that function as a tablespace. ?Is that not a supported
> >> > setup? ?There is probably a larger problem that the tablespace must be
> >> > located in a directory that has directory rename permission for
> >> > postgres. ?I have updated the pg_migrator INSTALL file to mention this
> >> > issue.
> >> >
> >> > As far as .old, we could create the tablespaces as *.new, but that kind
> >> > of defeats the existing recommended pg_migrator usage where we tell the
> >> > user to rename PGDATA to .old before running pg_migrator.
> >> >
> >> > It was actually Tom's idea months ago to put a version-specific
> >> > directory in the tablespace. ?I don't think it is necessary, and we can
> >> > live with the mount point limitation.
> >>
> >> What doesn't work if we just don't rename the tablespace at all? ?And
> >> can't we put some smarts into the backend to handle that thing?
> >
> > Well, when you restore the old dump's schema into the new server, the
> > tablespace directory path will be the same, so we had better not have
> > any directory there.
> 
> Well that seems like something you could work around by hacking the
> contents of the dump...

True, in --binary-upgrade mode, but what do we make it?  *.new?  What if
they want to have the same tablespace names after the upgrade?  It
really gets ugly if we are on a mount point because the tablespaces will
be in different file systems, which makes --link mode impossible, and
might create files in a filesystem that doesn't have enough space.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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