Re: [HACKERS] COPY with no WAL, in certain circumstances

On Sun, 2007-01-07 at 11:29 -0500, Tom Lane wrote:
> I wrote:
> > ... The active-portal kluge that you've just
> > mentioned is nothing but a kluge, proving that you thought of some cases
> > where it would fail. But I doubt you thought of everything.
>
> BTW, a sufficient counterexample for that kluge is that neither SPI or
> SQL-function execution use a separate portal for invoked commands. Thus
> testing whether there's only one active portal isn't sufficient to prove
> that you're not inside a function executing in serializable mode, and
> thus it could have a transaction snapshot predating the COPY.

Chewing the last pieces of my Bowler hat while reading. I don't have
many left ;-(

> It's conceivable that it's safe anyway, or could be made so with some
> rejiggering of the tests in tqual.c, but counting active portals doesn't
> do anything to help.

I'll rethink, but as you say, with separate proposal and patch.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com