Re: Making an app unviewable during system maintainance

> > Good point, though if this is a concern, the OP will probably use the > > built-in enforcement of referential integrity and transaction support > > of whatever database they are running. > > If a single database is spread over files A, B, and C, then in the time > it took for a naive backup to grab file A, files B and C may have > changed such that the database cannot be restored to an > internally-consistent state using files A, B, and C. At this point, > enforcement of referential integrity would actually work against you. Right, but if the database's built-in backup tool is used rather than the filesystem, it ought to respect the read/write locks that are a natural by-product of using begin/commit to wrap your transactions. E.g., a call to pg_dump should be guaranteed to pull the database in an internally-consistent state, if the application logic uses transactions correctly. I guess that's probably what you meant by "Use the DB to make the snapshot, then back up the snapshot." :) (I say "ought" and "should" because I'm no DB guru, myself) This popped up on /. yesterday, and it seems relevant: http://www.oreillynet.com/pub/wlg/4715 --------------------------------------------------------------------- michal migurski- contact info and pgp key: sf/ca http://mike.teczno.com/contact.html