Re: why do we need two snapshots per query?

On Fri, Nov 11, 2011 at 10:04 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
>> Tom, in that earlier thread you said you'd be doing something in this
>> release about that. Can you say more about what that was, and will you
>> be doing it still?
>
> http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=e6faf910d75027bdce7cd0f2033db4e912592bcc
>
> I think that largely supersedes what I understood your notion of a
> one-shot plan to be about, though perhaps I missed something?

I was looking at other use cases, specifically partitioning/partial indexes.

If we could be certain that a query was being executed immediately
then it would be possible to simplify expressions using stable
functions as if they were constants. My earlier patch did exactly
that.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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