Re: Potential G2-item cycles under serializable isolation

On Fri, Jun 12, 2020 at 10:14 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> Here's a new attempt at that. Attached, but I'll also just include
> the new paragraph here because it's short:

Slightly improved version, bringing some wording into line with
existing documentation. s/SQL Standard/SQL standard/, and explicitly
referring to "locking" implementations of RR and Ser (as we do already
a few paragraphs earlier, when discussing MVCC). My intention is to
push this to all branches in a couple of days if there is no other
feedback. I propose to treat it as a defect, because I agree that
it's weird and surprising that we don't mention SI, especially
considering the history of the standard levels. I mean, I guess it's
basically implied by all the stuff that section says about MVCC vs
traditional locking systems, and it's a super well known fact in our
hacker community, but not using the standard term of art is a strange
omission.

In future release perhaps we could entertain ideas like accepting the
name SNAPSHOT ISOLATION, and writing some more use-friendly guidance,
and possibly even reference the Generalized Isolation Level
Definitions stuff. I think it'd be a bad idea to stop accepting
REPEATABLE READ and inconvenience our users, though; IMHO it's
perfectly OK to stick with the current interpretation of the spec
while also acknowledging flaws and newer thinking through this new
paragraph.