pjmore commented on a change in pull request #1066:
URL: https://github.com/apache/arrow-datafusion/pull/1066#discussion_r720512539
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File path: datafusion/src/physical_plan/functions.rs
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@@ -543,6 +553,28 @@ macro_rules! invoke_if_unicode_expressions_feature_flag {
};
}
+///Function volatility determines when a function can be inlined or in the
future have evaluations elided when the arguments are the same
+///Immutable - a pure function which always remains the same
+///Stable - Maybe not required?. Used for functions which can modify the db
but are stable for multiple calls in statement
+///Volatile - Functions where output can vary for each call.
+///For more information see
https://www.postgresql.org/docs/current/xfunc-volatility.html
+#[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[repr(u32)]
+pub enum FunctionVolatility {
+ ///Immutable - a pure function which always remains the same
+ Immutable = 0,
+ ///Stable - Maybe not required?. Used for functions which can modify the
db but are stable for multiple calls in statement is this relevant for
datafusion as in mem?
+ Stable = 1,
+ ///Volatile - Functions where output can vary for each call.
+ Volatile = 2,
+}
+
+impl Default for FunctionVolatility {
Review comment:
That makes a lot of sense. I'll remove the default volatility.
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