"dandl" <david(at)andl(dot)org> writes:
> Are there specific requirements or things to do/avoid in order to use
> subtransactions (at the PL API level)?
There isn't, currently, any very hard-and-fast rule about what APIs
extensions should use or not use. My advice is to borrow freely
from existing PLs, particularly pl/pgsql. You might have to change
your code in future PG major versions, but that could happen anyway.
regards, tom lane