ozankabak commented on code in PR #11506:
URL: https://github.com/apache/datafusion/pull/11506#discussion_r1687128217
##########
datafusion/physical-expr/src/equivalence/properties.rs:
##########
@@ -1484,6 +1527,84 @@ impl Hash for ExprWrapper {
}
}
+/// Calculates the union (in the sense of `UnionExec`) `EquivalenceProperties`
+/// of `lhs` and `rhs` according to the schema of `lhs`.
+fn calculate_union_binary(
+ lhs: EquivalenceProperties,
+ mut rhs: EquivalenceProperties,
+) -> Result<EquivalenceProperties> {
+ // TODO: In some cases, we should be able to preserve some equivalence
Review Comment:
We plan to spend some time to fully complete this TODO item in the next
couple months or so 🚀
##########
datafusion/physical-expr/src/equivalence/properties.rs:
##########
@@ -1484,6 +1527,84 @@ impl Hash for ExprWrapper {
}
}
+/// Calculates the union (in the sense of `UnionExec`) `EquivalenceProperties`
+/// of `lhs` and `rhs` according to the schema of `lhs`.
+fn calculate_union_binary(
+ lhs: EquivalenceProperties,
+ mut rhs: EquivalenceProperties,
+) -> Result<EquivalenceProperties> {
+ // TODO: In some cases, we should be able to preserve some equivalence
+ // classes. Add support for such cases.
+
+ // Harmonize the schema of the rhs with the schema of the lhs (which is
the accumulator schema):
+ if !rhs.schema.eq(&lhs.schema) {
+ rhs = rhs.with_new_schema(Arc::clone(&lhs.schema))?;
+ }
+
+ // First, calculate valid constants for the union. A quantity is constant
+ // after the union if it is constant in both sides.
+ let constants = lhs
+ .constants()
+ .iter()
+ .filter(|const_expr| const_exprs_contains(rhs.constants(),
const_expr.expr()))
+ .map(|const_expr| {
+ // TODO: When both sides' constants are valid across partitions,
+ // the union's constant should also be valid if values are
+ // the same. However, we do not have the capability to
+ // check this yet.
+
ConstExpr::new(Arc::clone(const_expr.expr())).with_across_partitions(false)
+ })
+ .collect();
+
+ // Next, calculate valid orderings for the union by searching for prefixes
+ // in both sides.
+ let mut orderings = vec![];
+ for mut ordering in lhs.normalized_oeq_class().orderings {
+ // Progressively shorten the ordering to search for a satisfied prefix:
+ while !rhs.ordering_satisfy(&ordering) {
Review Comment:
exactly
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