Re: why do we need two snapshots per query?

Florian Pflug <fgp(at)phlo(dot)org> writes:
> On Nov11, 2011, at 16:18 , Robert Haas wrote:
>> In the extend query protocol scenario, it seems to me that keeping the
>> snapshot would be both wrong and a bad idea.

> Hm, but that'd penalize clients who use the extended query protocol, which
> they have to if they want to transmit out-of-line parameters. You could
> work around that by making the extended protocol scenario work like the
> simply protocol scenario if the unnamed statement and/or portal is used.

> Since clients presumably use pipelined Parse,Bind,Execute messages when
> using the unnamed statement and portal, they're unlikely to observe the
> difference between a snapshot taken during Parse, Bind or Execute.

I think it would be a seriously bad idea to allow the unnamed portal to
have semantic differences from other portals. We've gotten enough flak
about the fact that it had planner behavioral differences (enough so that
those differences are gone as of HEAD).

regards, tom lane