gabotechs commented on code in PR #15563:
URL: https://github.com/apache/datafusion/pull/15563#discussion_r2030623674
##########
datafusion/physical-expr/src/equivalence/properties/mod.rs:
##########
@@ -575,10 +576,35 @@ impl EquivalenceProperties {
// From the analysis above, we know that `[a ASC]` is satisfied.
Then,
// we add column `a` as constant to the algorithm state. This
enables us
// to deduce that `(b + c) ASC` is satisfied, given `a` is
constant.
- eq_properties = eq_properties
-
.with_constants(std::iter::once(ConstExpr::from(normalized_req.expr)));
+ eq_properties = eq_properties.with_constants(std::iter::once(
+ ConstExpr::from(Arc::clone(&normalized_req.expr)),
+ ));
}
- true
+
+ // All requirements are satisfied.
+ normalized_reqs.len()
+ }
+
+ /// Determines the longest prefix of `reqs` that is satisfied by the
existing ordering.
+ /// Returns that prefix as a new `LexRequirement`, and a boolean
indicating if all the requirements are satisfied.
+ pub fn extract_matching_prefix(
+ &self,
+ reqs: &LexRequirement,
+ ) -> (LexRequirement, bool) {
+ // First, standardize the given requirement:
+ let normalized_reqs = self.normalize_sort_requirements(reqs);
Review Comment:
I imagine that this will normalize cases where columns get aliased,
duplicate sort expressions, etc. But would this normalize cases where
expressions that do not alter the order are applied to columns? For example,
would `[int_column+1 DESC, int_column DESC]` be normalized to `[int_column
DESC]`? if that's the case, maybe adding a sql logic test that verifies that
the common sort prefix takes this into account?
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