Alexander Staubo wrote:
On Oct 2, 2006, at 22:17 , Madison Kelly wrote:
I am (re)writing a backup program and I want to add a section for
backing up pSQL DBs. In the planning steps (making sure a given
destination has enough space) I try to calculate how much space will
be needed by a 'pg_dump' run *before* actually dumping it.
Is there a relatively easy way to do that? Moreso, if it possible to
do this from an unpriviledged account? If not, is there a way to add
the permissions to a specific pg user to allow that user to perform this?
You could dump the database to /dev/null, piping it through wc to catch
the size, but that would of course be wasteful.
You could count the disk space usage of the actual stored tuples, though
this will necessarily be inexact:
http://www.postgresql.org/docs/8.1/static/diskusage.html
Or you could count the size of the physical database files
(/var/lib/postgresql or wherever). While these would be estimates, you
could at least guarantee that the dump would not *exceed* the esimtate.
Keep in mind that pg_dump can compress the dump and (iirc) will do so by
default when you use the custom format (-Fc or --format=c).
Alexander.
Heh, that looks like just the article I would have wanted if I had
properly RTFM. :D
Many thanks!!
Madi
