Re: CASE WHEN idiomatic for functions with side-effect?

"Joel Jacobson" <joel@compiler.org> writes:
> Is it idiomatic and safe to use
> SELECT
>   CASE boolean_expression WHEN TRUE THEN function_with_side_effects() END
> in a query to ensure the function_with_side_effects() is only
> execute if boolean_expression is true?

As long as function_with_side_effects() is properly marked volatile,
it's safe (whether it's idiomatic is in the eye of the beholder).

The issue with the divide-by-zero example is that the division operator
is marked immutable, so if the planner sees that it has constant arguments
it will try to simplify-on-sight, even within a CASE expression.

            regards, tom lane