Joshua Tolley <eggyknap@gmail.com> writes:
> It then does some work to determine whether the result in "function" is
> valid or not. So I got to wondering, what's the lifetime of the
> FunctionCallInfoinfo object passed to the call handler function?
Query lifespan, usually. There are counterexamples on both sides,
but as a rule it's expected that it's worthwhile for a function to
cache anything it can in the fcinfo->flinfo->fn_extra structure.
If it's not worthwhile, that's the caller's fault not the function's.
regards, tom lane