On Tue, 2010-10-26 at 22:03 -0400, Robert Haas wrote: > On Tue, Oct 26, 2010 at 9:59 PM, Josh Berkus <j...@agliodbs.com> wrote: > > > >> If you set wal_keep_segments=0, archive_mode=on, and > >> archive_command=<something>, you might run out of disk space. > >> > >> If you set wal_keep_segments=-1, you might run out of disk space. > >> > >> Are you any more screwed in the second case than you are in the first > >> case? > > > > It is the same to the user either way. In either case you have to > > change some settings and restart the master. > > Except that changing wal_keep_segments doesn't require restarting the master. > > The point of allowing -1 was to allow someone to set it to that value > temporarily, to be able to do a hot backup without having to guess how > large to set it. If you don't have enough disk space for a backup to > complete, you're kind of hosed either way.
You're not hosed either way. Fujii designed this carefully to avoid that and it works. The case of archive_command failing isn't comparable because that is a failure case, not a normal working server. You don't need to guess the setting of wal_keep_segments. It's a safety net that has been deliberately created to avoid the crash that would otherwise happen. I've not heard a better proposal, yet, though I too am hopeful there is a better one. This is all described in my new book on PostgreSQL Administration, available from the link below. I'm told that everything you need is also in the docs. -- Simon Riggs http://www.2ndQuadrant.com/books/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers