But in the meantime, given the choice of phantom reads or G2-item, I think I'd pick blocking phantom reads.
Well... it's not quite so straightforward. SI still allows some phantoms. It only prohibits some of them.
In PostgreSQL's case, if they somehow made repeatable read to prevent G2-item without sacrificing the phantom reads, would that mean repeatable read is then "serializable" according to the ANSI definition?
I'm not quite sure I follow--If you're asking whether snapshot isolation (Postgres "Repeatable Read") plus preventing G2-item is serializable, the answer is no--that model would still allow G2 in general--specifically, cycles involving non-adjacent rw dependencies with predicates.
Well... it's not quite so straightforward. SI still allows some phantoms. It only prohibits some of them.
In PostgreSQL's case, if they somehow made repeatable read to prevent G2-item without sacrificing the phantom reads, would that mean repeatable read is then "serializable" according to the ANSI definition?
I'm not quite sure I follow--If you're asking whether snapshot isolation (Postgres "Repeatable Read") plus preventing G2-item is serializable, the answer is no--that model would still allow G2 in general--specifically, cycles involving non-adjacent rw dependencies with predicates.