On Mon, May 10, 2010 at 2:59 PM, Joshua D. Drake
<jd@commandprompt.com> wrote:
On Mon, 2010-05-10 at 17:33 +0000, Greg Sabino Mullane wrote:
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>
> > I would like to replicate the following Unix pipe within a Perl script,
> > perhaps using DBD::Pg:
> >
> >
> > % pg_dump -Z9 -Fc -U <DB_USER> <FROM_DB> | pg_restore -v -d <TO_DB> -p
> > <SSH_TUNNEL_PORT> -h localhost -U <DB_USER>
> >
> > Of course, I can try to use Perl's system, and the like, to run this pipe
> > verbatim, but I this as a last-resort approach.
> >
> > Is there a more direct way?
>
> If you mean emulate the pg_dump, no. pg_dump does a *lot* of stuff behind
> the scenes, and trying to rewrite all that in Perl would be madness. And I
> say that having written some serious madness into DBD::Pg already :). Stick
> with the shell script, even if it means calling system.
>
> If you simply want to avoid the pipes, you can think about calling pg_dump
> from the remote box, using a authorized_keys with a specific command in it,
> and other tricks, but nothing will be as straightforward and error proof
> as the line you gave, I suspect.
With one minor exception. I don't think he needs -Z9 since he is using
SSH which will compress anyway.
Actually, that was a mistake on my part. That should have been "-Ft" rather than "-Z9 -Fc", since I *don't* want compression (most of the data being transmitted consists of highly incompressible blobs anyway). Regarding SSH, my understanding is that to get compression one needs to pass to it the -C flag at the time of creating the tunnel. But my grasp of these details is tenuous as best.
~K
