Re: [PERFORM] optimizing immutable vs. stable function calls?

On 1/18/17 6:09 PM, David G. Johnston wrote:
> ​That would not be a productive exercise for me, or most people who just
> want
> some idea of what to expect in terms of behavior when they write and use a
> Stable function (Immutable and Volatile seem fairly easy to reason about).

Yeah, this isn't an uncommon question for users to have, and "read the
code" isn't a great answer.

If there's a README or comment block that describes this, that might be
a reasonable compromise.

It would certainly be useful to document how to push the planner in the
right direction as well. I didn't realize that SELECT ... (SELECT
slow_stable_function()) was a thing until reading this thread.
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