Nice, that has cleared it up. I am on 8.1 also. On my test box, a standard dump took 6m 26sec & a -Fc dump took 11min 2sec. That's not a great difference, but the size difference is quite noticeable. Thanks for your help. Steve. On Fri, 15 Aug 2008 02:15:25 +0200, Thomas Jacob <jacob@xxxxxxxxxxxxx> wrote: > On Fri, Aug 15, 2008 at 09:26:18AM +1000, steve@xxxxxxxxxxxxxxxxxx wrote: >> G'day, >> >> I am just running a straight pg_dump with no options. >> With the -Fc option the DB size is reduced to about: 700MB >> >> Is the -Fc a compressed format? Are there any limitations or side > effects >> to using this output, is it slower?? etc etc. Can this output be > restored >> via the normal method of: psql dbname < sql.dump > > Yes -Fc is a compressed format. From the man page of pg_dump: > > "custom: Output a custom archive suitable for input into pg_restore. > This is the most flexible format in that it allows reordering of loading > data as well as object definitions. This format is also compressed by > default." > > Whether or not the dump takes less or more time probably depends > on your spare CPU vs your spare IO capacity, in general I'd > say it isn't slower, given today's CPU, but I haven't measured > this. > > For restoring the DB you need to run the dump through pg_restore first, > which gives you various dials to control what to restore > and how, and then feed it into psql as usual. This gives you > more flexibility than with the plain SQL dump. Also, you > can recreate a plain SQL dump with pg_restore should > you require one. > > One drawback could be that if you lose your DB and something > also damages parts of your dumps, a compressed format might mean you can't > restore any data at all, vs. at least some data > with plain SQL dump. But that's not a very likely > scenario, is it? ;-) > > Also, you can't always restore from an -Fc dump, if > your pg_restore version is much older than the one that > particular dump was created with. For instance, trying > to restore an 8.3.3 dump with a 7.4.19 pg_restore I > get: > > "pg_restore: [archiver] unsupported version (1.10) in file header" > > When I use a 8.1.11 pg_restore, it seems to work fine. > But that's hardly a suprising result. > > Thomas
