support expression cluster key
@@ -626,7 +626,7 @@ fn get_maybe_monotonic(op: &str, args: Expressions) -> Result<bool> {
Ok(true)
}
-fn check_maybe_monotonic(expr: &Expression) -> Result<bool> {
+pub fn check_maybe_monotonic(expr: &Expression) -> Result<bool> {
match expr {
Expression::Literal { .. } => Ok(true),
Expression::Column { .. } => Ok(true),
