Re: pg_dump

On Thu, Oct 29, 2015 at 10:51:20AM -0400, Tom Lane wrote:
> =?koi8-r?B?5M3J1NLJyiD3z9LPzsnO?= <carriingfate92(at)yandex(dot)ru> writes:
> >> It's a problem. See this recent discussion:
> >> http://www.postgresql.org/message-id/flat/20150710115735(dot)GH26521(at)alap3(dot)anarazel(dot)de
>
> > Postgresmen, we have a SQL function "current_database", which can be called by statement "SELECT CURRENT_CATALOG".
>
> > If we will use CURRENT_CATALOG keyword, we can update syntax of COMMENT statement:
>
> > COMMENT ON DATABASE CURRENT_CATALOG IS 'comment';
>
> > And pg_dump will create this line for database. What are you think about this idea?
>
> We don't need hasty patches. What we need is a re-think of the division
> of labor between pg_dump and pg_dumpall. Up to now, pg_dump has only been
> charged with dumping/restoring the data "inside" an individual database,
> not with handling any database-level properties. Those are the
> responsibility of pg_dumpall.
>
> I'd be the first to agree that maybe this wasn't the best design, but at
> least it's consistent. If we're going to change things, we need to start
> by deciding where we're going to re-draw the line, and figuring out what
> sort of impact that will have in terms of compatibility considerations
> and users' backup/restore procedures.

In this vein, I'd like humbly to suggest that we draw the line in a
way that finishes the already accomplished work of excluding
pg_dumpall entirely. We should probably leave a pg_dumpall-compatible
wrapper for pg_dump for a few versions, but not if doing so cramps
development.

What pg_dumpall now still does that pg_dump doesn't is, as far as I
know:

- Whole-instance dumping (its original purpose, as far as I can tell)
- Auth (roles/secrets)
- Tablespaces

I believe that a relatively short patch to pg_dump would allow us to
make better versions of at least the first two. By better, I mean,

- Not require that a whole-instance dump be in a single file, and
- Be able to dump only the auth stuff relevant to the specified DB
objects.

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

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