Martijn van Oosterhout <kleptog@svana.org> writes:
> - Is there a way to detect if a snapshot has been started and creating
> one if there hasn't. I've seen the snapshot related functions but I
> don't feel comfortable sticking them in my type input function just to
> fix this. Is it safe?
This would be a pretty bad idea IMHO. The setting of the first snapshot
in a transaction is a significant event, and it should not happen in
random places like type-specific input functions.
A long-term solution to this might be to do what's envisioned in this
comment in parse_coerce.c:
* XXX if the typinput function is not immutable, we really ought to * postpone evaluation of the
functioncall until runtime. But * there is no way to represent a typinput function call as an *
expressiontree, because C-string values are not Datums. (XXX * This *is* possible as of 7.3, do we want to do
it?)
I'm a bit concerned about the possible side-effects of this on existing
behavior, though. In particular constructs like'now'::timestamp
would change behavior subtly.
regards, tom lane