On Fri, Oct 4, 2013 at 5:04 AM, Marko Tiikkaja <marko@joh.to> wrote:
> I might be completely in the woods here, but I believe something like this
> was attempted by Karol earlier, and it failed if two concurrent transactions
> did something similar to:
>
> UPDATE foo SET a = a + 1 RETURNING BEFORE.a;
>
> Both of them would see BEFORE.a = 0, because that's what the "a" evaluated
> to from the tuple we got before EvalPlanQual.
>
> But maybe what you're suggesting doesn't have this problem?
Hmm, it probably does. That explains why there are executor changes
here; I guess they need some comments to explain their purpose.
--
Robert Haas
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