Re: serializable read only deferrable

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Attached.

> Accomplished more through mimicry (based on setting transaction
> isolation level) than profound understanding of the code involved;
> but it passes all regression tests on both `make check` and `make
> installcheck-world`. This includes a new regression test that an
> attempt to change it after a query fails. I've poked at it with
> various ad hoc tests, and it is behaving as expected in those.

Hmm. This patch disallows the case of creating a read-only
subtransaction of a read-write parent. That's a step backwards.
I'm not sure how we could enforce that the property not change
after the first query of a subxact, but maybe we don't care that much?
Do your optimizations pay attention to local read-only in a subxact?

regards, tom lane