On 13 November 2011 16:42, Tom Lane <t...@sss.pgh.pa.us> wrote: > Thom Brown <t...@linux.com> writes: >> I don't know if this has been discussed before, but would it be >> feasible to introduce the ability to detach and attach databases? (if >> you're thinking "stop right there" skip to the end) > > ... skipping ... > >> It's just a vague idea, and I'm kind of expecting responses to begin >> with "Well for a start, this couldn't possible begin to work >> because..." but that's par for the course. ;) > > The main reason this doesn't work is XID management. > > It's barely possible you could make it work if you first locked all > other sessions out of the DB and then froze every XID in the database, > but that's a sufficiently heavyweight operation to make it of dubious > value. > > You'd also have to think of some way to ensure that page LSNs in the > database are lower than the current WAL endpoint in the receiver. > > The other thing I'd be concerned about is inconsistency with the global > system catalogs in the receiving installation. Consider roles for > example: the receiver might not have the same set of roles, probably > wouldn't have the same OIDs for those roles, and definitely would be > missing the pg_shdepend entries that describe which objects in the > transported database are owned by which roles.
I feared such a non-traversable terrain would prevent it being possible. Oh well. Thanks for the explanation though. -- Thom Brown Twitter: @darkixion IRC (freenode): dark_ixion Registered Linux user: #516935 EnterpriseDB UK: 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
