On Tue, Jan 12, 2021 at 1:14 AM Joel Jacobson <j...@compiler.org> wrote:
> Is it idiomatic and safe to use > > SELECT > CASE boolean_expression WHEN TRUE THEN function_with_side_effects() END > As long as function_with_side_effects() is defined volatile it is forced to be executed at runtime, once per row. That situation is always protected by the case expression. > "related cases that don't obviously involve constants can occur in queries > executed within functions, since the values of function arguments and local > variables can be inserted into queries as constants for planning purposes. > Within PL/pgSQL functions, for example, using an IF-THEN-ELSE statement to > protect a risky computation is much safer than just nesting it in > a CASE expression." > > The affected real code: > https://github.com/truthly/uniphant/blob/rls/FUNCTIONS/api/verify_assertion.sql > The relevant function takes in a column argument - it is thus impossible for the planner to evaluate the expression. And, as above, the planner respects the "volatile" attribute of functions. David J.
