On Tue, Oct 26, 2010 at 8:27 AM, Simon Riggs <si...@2ndquadrant.com> wrote: > On Thu, 2010-10-21 at 20:57 -0400, Robert Haas wrote: > >> Very true. But the lack of a -1 setting for wal_keep_segments means >> that if you would like to take a backup without archiving, you must >> set wal_keep_segments to a value greater than or equal to the rate at >> which you generate WAL segments multiplied by the time it takes you to >> run a backup. If that doesn't qualify as requiring arcane knowledge, >> I'm mystified as to what ever could. > > People are missing the point here: > > You have to put the WAL files *somewhere* while you do the base backup. > PostgreSQL can't itself work out where that is, nor can it work out > ahead of time how big it will need to be, since it is up to you how you > do your base backup. Setting a parameter to -1 doesn't make the problem > go away, it just pretends and hopes it doesn't exist, but screws you > badly if you do hit the wall.
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? Why? -- 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
