Re: Practical maximums (was Re: PostgreSQL theoretical

On Mon, 2006-08-07 at 14:51, Ron Johnson wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Scott Marlowe wrote:
> > On Mon, 2006-08-07 at 13:51, Ron Johnson wrote:
> >> -----BEGIN PGP SIGNED MESSAGE-----
> >> Hash: SHA1
> >>
> >> Jeff Davis wrote:
> >>> On Mon, 2006-07-31 at 09:53 -0500, Ron Johnson wrote:
> >
> >>> pg_dump just produces output. You could pretty easily stripe that output
> >>> across multiple devices just by using some scripts. Just make sure to
> >>> write a script that can reconstruct the data again when you need to
> >>> restore.
> >> But doesn't that mean that pg_dump must dump to disk?
> >>
> >> With a *big* database, that's a whole lot of extra kit (not just
> >> spindles) to buy.
> >
> > I'm certain you can backup direct to tape, as I've done it in the past
> > with postgresql. This was in the day of 4 gig 4 mm tape drives...
>
> Sure. That's why tar is named *Tape* ARchive.
>
> Going along with the example of the 4GB 4mm tape drive, and to
> simplify, we are *not* using compression (neither on the drive or
> s/w gzip or bzip):
>
> Say we have a 7GB database. Is there a way to way to use 2 tape
> drives... Argh, I guess not, since the Unix pipe mentality presumes
> that the mode of operation will be:
> $ pg_dump /some/database | tar cvfz /dev/st0/db.tgz
>
> What would be darned useful (but only, I think, with heavy usage of
> tablespaces) is:
> $ pg_tapedump /some/database /dev/st0,/dev/st1,/dev/st2,/dev/st3

Oh, I see where you were headed.

I've found a bit here and there googling about for multiplex and tar,
and found an IO:Multiplex module for perl.

I don't see why someone couldn't make use of it to create some kind of
system where you'd do:

pg_dump dbname | perl mulitiplexscript device1,device2,device3,devicen

No need for postgresql to support it directly. Restoring would likewise
just be a reverse operation.