Re: Better support of exported snapshots with pg_dump

On Fri, Oct 17, 2014 at 12:19 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Wed, Oct 15, 2014 at 1:06 AM, Andres Freund <andres(at)2ndquadrant(dot)com>
> wrote:
> > I personally think we should just disregard the race here and add a
> > snapshot parameter. The race is already there and not exactly
> > small. Let's not kid ourselves that hiding it solves anything.
> I, too, favor that plan.
>
Two votes in favor of that from two committers sounds like a deal. Here is
an refreshed version of the patch introducing --snapshot from here, after
fixing a couple of things and adding documentation:
http://www.postgresql.org/message-id/CA+U5nMK9+TTCff_-4MfdxWHnASTAuHuq7u7uedD57vaY28AsQA@mail.gmail.com

When the snapshot specified by user is not a valid one, here is the error
returned by pg_dump:
$ pg_dump --snapshot 'ppo'
pg_dump: [archiver (db)] query failed: ERROR: invalid snapshot identifier:
"ppo"
pg_dump: [archiver (db)] query was: SET TRANSACTION SNAPSHOT 'ppo'
I thinks that's fine, and it makes the code lighter to rely on the existing
error machinery.

Regards,
--
Michael