Re: CatCache state reversing

Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> writes:
> What I'm currently thinking is that for each entry in the cache, we'll
> save the current refcount at subtransaction start, and then restore it
> at subtransaction abort. At subtransaction commit, the parent's
> refcount will be updated with the subtransaction's refcount, which can
> be greater than zero.

No it can't. The reference counts should all be exactly the same at
subtrans start and subtrans commit, else there was a reference leak.
This corresponds to complaining if the count isn't zero at main trans
commit. I don't see that there should ever be a situation where a
subtrans releases a refcount acquired by an outer trans or vice versa.

While you're looking at that, what about the cache invalidation logic?
I think subtrans commit is probably not different from
CommandCounterIncrement, but I'm not sure how to clean up the caches and
the pending-inval lists on subtrans abort.

regards, tom lane