mlw <markw(at)mohawksoft(dot)com> writes:
>> Hmm ... given that ftss refers to external files, is it a good idea to
>> mark it cachable?
> This I don't understand. What is the lifetime of a value that "iscacheable?"
Forever. cachable says it's OK to reduce "func(constant)" to "constant"
on sight. Right now it's not really forever because we don't save query
plans for very long (unless they're inside a plpgsql function) ... but
if you have a function that depends on any outside data besides its
arguments, you'd be ill-advised to mark it cachable.
regards, tom lane