Re: User's responsibility when using a chain of "immutable" functions?

Pavel Stehule <pavel.stehule@gmail.com> writes:
> st 29. 6. 2022 v 7:46 odesílatel Tom Lane <tgl@sss.pgh.pa.us> napsal:
>> ... that result has discouraged most people from spending much
>> time on mechanically checking such things.  If you declare a function
>> immutable, Postgres will believe you; the consequences if you lied
>> are on your own head.

> We cannot ensure that the function is immutable, but we can detect that the
> function is not very probably immutable (in execution time).

Sure, there are a lot of easy cases where we could say "that's
obviously not immutable".  But is it worth spending engineering
effort and runtime on that?  I suspect the cases that people
might actually mess up are less obvious, so that we might
accomplish little more than offering a false sense of security.

                        regards, tom lane