On Mon, Oct 18, 2010 at 3:21 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Mon, Oct 18, 2010 at 3:05 PM, Bruce Momjian <br...@momjian.us> wrote: >>> Robert Haas wrote: >>>> I haven't yet been convinced we need or want to relax the rule about >>>> the directory being empty. >>> >>> Uh, how would pg_upgrade work then? It would require renaming the >>> top-level tablespace directory, which might require root permissions. > >> Huh? Whether or not we choose to store our data files in a >> subdirectory is an independent question from whether or not we verify >> that the directory is empty before we start scribbling on it. > > No, you're missing the point. If a pre-9.0 DB is told that tablespace T > has location '/foo/bar', it'll start creating stuff right in /foo/bar. > pg_upgrade will tell 9.0 to create the tablespace with location /foo/bar > as well. If 9.0 refuses because that directory contains stuff already, > the upgrade will fail. Instead, we make a version-numbered subdirectory > and start creating 9.0's stuff there. > > Given the use of the version-numbered subdirectory, I see no real merit > in insisting that the parent directory be empty anyway. It'd be > precisely analogous to "initdb -D /foo/bar/data" insisting that /foo/bar > be empty, which we have never done and nobody's ever suggested would be > a good idea.
There aren't a lot of sane use cases for storing other bits of data inside either $PGDATA or one of your tablespace directories. However... I guess you might have something like an empty lost+found directory if you're creating the tablespace directly on top of a mount point, and perhaps there's a good argument that that shouldn't interfere. Or, I think I've run across NAS devices where every directory on the system contains a subdirectory called .snapshot, or something like that. So maybe insisting on empty isn't right after all. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
