LexRequirement as a struct, instead of a type

datafusion/core/src/datasource/listing/table.rs

@@ -53,6 +53,7 @@ use datafusion_physical_expr::{
 
 use async_trait::async_trait;
 use datafusion_catalog::Session;
+use datafusion_physical_expr_common::sort_expr::LexRequirement;
 use futures::{future, stream, StreamExt, TryStreamExt};
 use itertools::Itertools;
 use object_store::ObjectStore;
@@ -987,12 +988,12 @@ impl TableProvider for ListingTable {
                 ))?
                 .clone();
             // Converts Vec<Vec<SortExpr>> into type required by execution plan to specify its required input ordering
-            Some(
+            Some(LexRequirement::new(
                 ordering
                     .into_iter()
                     .map(PhysicalSortRequirement::from)
                     .collect::<Vec<_>>(),
-            )
+            ))
         } else {
             None
         };

datafusion/core/src/physical_optimizer/enforce_distribution.rs

@@ -1272,7 +1272,7 @@ fn ensure_distribution(
                         // Make sure to satisfy ordering requirement:
                         child = add_sort_above_with_check(
                             child,
-                            required_input_ordering.to_vec(),
+                            required_input_ordering.clone(),
                             None,
                         );
                     }

datafusion/core/src/physical_optimizer/projection_pushdown.rs

@@ -54,6 +54,7 @@ use datafusion_physical_expr::{
 use datafusion_physical_plan::streaming::StreamingTableExec;
 use datafusion_physical_plan::union::UnionExec;
 
+use datafusion_physical_expr_common::sort_expr::LexRequirement;
 use datafusion_physical_optimizer::PhysicalOptimizerRule;
 use itertools::Itertools;
 
@@ -334,10 +335,10 @@ fn try_swapping_with_output_req(
         return Ok(None);
     }
 
-    let mut updated_sort_reqs = vec![];
+    let mut updated_sort_reqs = LexRequirement::new(vec![]);
     // None or empty_vec can be treated in the same way.
     if let Some(reqs) = &output_req.required_input_ordering()[0] {
-        for req in reqs {
+        for req in &reqs.inner {
             let Some(new_expr) = update_expr(&req.expr, projection.expr(), false)? else {
                 return Ok(None);
             };
@@ -1995,7 +1996,7 @@ mod tests {
         let csv = create_simple_csv_exec();
         let sort_req: Arc<dyn ExecutionPlan> = Arc::new(OutputRequirementExec::new(
             csv.clone(),
-            Some(vec![
+            Some(LexRequirement::new(vec![
                 PhysicalSortRequirement {
                     expr: Arc::new(Column::new("b", 1)),
                     options: Some(SortOptions::default()),
@@ -2008,7 +2009,7 @@ mod tests {
                     )),
                     options: Some(SortOptions::default()),
                 },
-            ]),
+            ])),
             Distribution::HashPartitioned(vec![
                 Arc::new(Column::new("a", 0)),
                 Arc::new(Column::new("b", 1)),
@@ -2041,7 +2042,7 @@ mod tests {
         ];
 
         assert_eq!(get_plan_string(&after_optimize), expected);
-        let expected_reqs = vec![
+        let expected_reqs = LexRequirement::new(vec![
             PhysicalSortRequirement {
                 expr: Arc::new(Column::new("b", 2)),
                 options: Some(SortOptions::default()),
@@ -2054,7 +2055,7 @@ mod tests {
                 )),
                 options: Some(SortOptions::default()),
             },
-        ];
+        ]);
         assert_eq!(
             after_optimize
                 .as_any()

datafusion/core/src/physical_optimizer/sort_pushdown.rs

@@ -173,7 +173,8 @@ fn pushdown_requirement_to_children(
         let child_plan = plan.children().swap_remove(0);
         match determine_children_requirement(parent_required, request_child, child_plan) {
             RequirementsCompatibility::Satisfy => {
-                let req = (!request_child.is_empty()).then(|| request_child.to_vec());
+                let req = (!request_child.is_empty())
+                    .then(|| LexRequirement::new(request_child.to_vec()));
                 Ok(Some(vec![req]))
             }
             RequirementsCompatibility::Compatible(adjusted) => Ok(Some(vec![adjusted])),
@@ -189,7 +190,9 @@ fn pushdown_requirement_to_children(
             .requirements_compatible(parent_required, &sort_req)
         {
             debug_assert!(!parent_required.is_empty());
-            Ok(Some(vec![Some(parent_required.to_vec())]))
+            Ok(Some(vec![Some(LexRequirement::new(
+                parent_required.to_vec(),
+            ))]))
         } else {
             Ok(None)
         }
@@ -211,15 +214,17 @@ fn pushdown_requirement_to_children(
             .eq_properties
             .requirements_compatible(parent_required, &output_req)
         {
-            let req = (!parent_required.is_empty()).then(|| parent_required.to_vec());
+            let req = (!parent_required.is_empty())
+                .then(|| LexRequirement::new(parent_required.to_vec()));
             Ok(Some(vec![req]))
         } else {
             Ok(None)
         }
     } else if is_union(plan) {
         // UnionExec does not have real sort requirements for its input. Here we change the adjusted_request_ordering to UnionExec's output ordering and
         // propagate the sort requirements down to correct the unnecessary descendant SortExec under the UnionExec
-        let req = (!parent_required.is_empty()).then(|| parent_required.to_vec());
+        let req = (!parent_required.is_empty())
+            .then(|| LexRequirement::new(parent_required.to_vec()));
         Ok(Some(vec![req; plan.children().len()]))
     } else if let Some(smj) = plan.as_any().downcast_ref::<SortMergeJoinExec>() {
         // If the current plan is SortMergeJoinExec
@@ -277,7 +282,8 @@ fn pushdown_requirement_to_children(
         } else {
             // Can push-down through SortPreservingMergeExec, because parent requirement is finer
             // than SortPreservingMergeExec output ordering.
-            let req = (!parent_required.is_empty()).then(|| parent_required.to_vec());
+            let req = (!parent_required.is_empty())
+                .then(|| LexRequirement::new(parent_required.to_vec()));
             Ok(Some(vec![req]))
         }
     } else {
@@ -331,7 +337,8 @@ fn determine_children_requirement(
     {
         // Parent requirements are more specific, adjust child's requirements
         // and push down the new requirements:
-        let adjusted = (!parent_required.is_empty()).then(|| parent_required.to_vec());
+        let adjusted = (!parent_required.is_empty())
+            .then(|| LexRequirement::new(parent_required.to_vec()));
         RequirementsCompatibility::Compatible(adjusted)
     } else {
         RequirementsCompatibility::NonCompatible
@@ -471,7 +478,7 @@ fn shift_right_required(
         })
         .collect::<Vec<_>>();
     if new_right_required.len() == parent_required.len() {
-        Ok(new_right_required)
+        Ok(LexRequirement::new(new_right_required))
     } else {
         plan_err!(
             "Expect to shift all the parent required column indexes for SortMergeJoin"
@@ -574,7 +581,7 @@ fn handle_custom_pushdown(
             .iter()
             .map(|&maintains_order| {
                 if maintains_order {
-                    Some(updated_parent_req.clone())
+                    Some(LexRequirement::new(updated_parent_req.clone()))
                 } else {
                     None
                 }

datafusion/physical-expr-common/src/sort_expr.rs

@@ -19,6 +19,7 @@
 
 use std::fmt::Display;
 use std::hash::{Hash, Hasher};
+use std::ops::Deref;
 use std::sync::Arc;
 
 use crate::physical_expr::PhysicalExpr;
@@ -222,11 +223,13 @@ impl PhysicalSortRequirement {
     pub fn from_sort_exprs<'a>(
         ordering: impl IntoIterator<Item = &'a PhysicalSortExpr>,
     ) -> LexRequirement {
-        ordering
-            .into_iter()
-            .cloned()
-            .map(PhysicalSortRequirement::from)
-            .collect()
+        LexRequirement::new(
+            ordering
+                .into_iter()
+                .cloned()
+                .map(PhysicalSortRequirement::from)
+                .collect(),
+        )
     }
 
     /// Converts an iterator of [`PhysicalSortRequirement`] into a Vec
@@ -264,9 +267,55 @@ pub type LexOrdering = Vec<PhysicalSortExpr>;
 /// a reference to a lexicographical ordering.
 pub type LexOrderingRef<'a> = &'a [PhysicalSortExpr];
 
-///`LexRequirement` is an alias for the type `Vec<PhysicalSortRequirement>`, which
+///`LexRequirement` is an struct containing a `Vec<PhysicalSortRequirement>`, which
 /// represents a lexicographical ordering requirement.
-pub type LexRequirement = Vec<PhysicalSortRequirement>;
+#[derive(Debug, Default, Clone, PartialEq)]
+pub struct LexRequirement {
+    pub inner: Vec<PhysicalSortRequirement>,
+}
+
+impl LexRequirement {
+    pub fn new(inner: Vec<PhysicalSortRequirement>) -> Self {
+        Self { inner }
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = &PhysicalSortRequirement> {
+        self.inner.iter()
+    }
+
+    pub fn push(&mut self, physical_sort_requirement: PhysicalSortRequirement) {
+        self.inner.push(physical_sort_requirement)
+    }
+}
+
+impl Deref for LexRequirement {
+    type Target = [PhysicalSortRequirement];
+
+    fn deref(&self) -> &Self::Target {
+        self.inner.as_slice()
+    }
+}
+
+impl FromIterator<PhysicalSortRequirement> for LexRequirement {
+    fn from_iter<T: IntoIterator<Item = PhysicalSortRequirement>>(iter: T) -> Self {
+        let mut lex_requirement = LexRequirement::new(vec![]);
+
+        for i in iter {
+            lex_requirement.inner.push(i);
+        }
+
+        lex_requirement
+    }
+}
+
+impl IntoIterator for LexRequirement {
+    type Item = PhysicalSortRequirement;
+    type IntoIter = std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.inner.into_iter()
+    }
+}
 
 ///`LexRequirementRef` is an alias for the type &`[PhysicalSortRequirement]`, which
 /// represents a reference to a lexicographical ordering requirement.

datafusion/physical-expr/src/equivalence/class.rs

@@ -418,7 +418,7 @@ impl EquivalenceGroup {
         // Normalize the requirements:
         let normalized_sort_reqs = self.normalize_sort_requirements(&sort_reqs);
         // Convert sort requirements back to sort expressions:
-        PhysicalSortRequirement::to_sort_exprs(normalized_sort_reqs)
+        PhysicalSortRequirement::to_sort_exprs(normalized_sort_reqs.inner)
     }
 
     /// This function applies the `normalize_sort_requirement` function for all
@@ -428,12 +428,12 @@ impl EquivalenceGroup {
         &self,
         sort_reqs: LexRequirementRef,
     ) -> LexRequirement {
-        collapse_lex_req(
+        collapse_lex_req(LexRequirement::new(
             sort_reqs
                 .iter()
                 .map(|sort_req| self.normalize_sort_requirement(sort_req.clone()))
                 .collect(),
-        )
+        ))
     }
 
     /// Projects `expr` according to the given projection mapping.

datafusion/physical-expr/src/equivalence/mod.rs

@@ -48,7 +48,7 @@ pub fn collapse_lex_req(input: LexRequirement) -> LexRequirement {
             output.push(item);
         }
     }
-    output
+    LexRequirement::new(output)
 }
 
 /// Adds the `offset` value to `Column` indices inside `expr`. This function is

datafusion/physical-expr/src/equivalence/properties.rs

@@ -515,8 +515,9 @@ impl EquivalenceProperties {
     ) -> Option<LexRequirement> {
         let mut lhs = self.normalize_sort_requirements(req1);
         let mut rhs = self.normalize_sort_requirements(req2);
-        lhs.iter_mut()
-            .zip(rhs.iter_mut())
+        lhs.inner
+            .iter_mut()
+            .zip(rhs.inner.iter_mut())
             .all(|(lhs, rhs)| {
                 lhs.expr.eq(&rhs.expr)
                     && match (lhs.options, rhs.options) {

datafusion/physical-plan/src/aggregates/mod.rs

@@ -370,21 +370,23 @@ impl AggregateExec {
         // prefix requirements with this section. In this case, aggregation will
         // work more efficiently.
         let indices = get_ordered_partition_by_indices(&groupby_exprs, &input);
-        let mut new_requirement = indices
-            .iter()
-            .map(|&idx| PhysicalSortRequirement {
-                expr: Arc::clone(&groupby_exprs[idx]),
-                options: None,
-            })
-            .collect::<Vec<_>>();
+        let mut new_requirement = LexRequirement::new(
+            indices
+                .iter()
+                .map(|&idx| PhysicalSortRequirement {
+                    expr: Arc::clone(&groupby_exprs[idx]),
+                    options: None,
+                })
+                .collect::<Vec<_>>(),
+        );
 
         let req = get_finer_aggregate_exprs_requirement(
             &mut aggr_expr,
             &group_by,
             input_eq_properties,
             &mode,
         )?;
-        new_requirement.extend(req);
+        new_requirement.inner.extend(req);
         new_requirement = collapse_lex_req(new_requirement);
 
         // If our aggregation has grouping sets then our base grouping exprs will

datafusion/physical-plan/src/sorts/sort.rs

@@ -792,7 +792,9 @@ impl SortExec {
     ) -> PlanProperties {
         // Determine execution mode:
         let sort_satisfied = input.equivalence_properties().ordering_satisfy_requirement(
-            PhysicalSortRequirement::from_sort_exprs(sort_exprs.iter()).as_slice(),
+            PhysicalSortRequirement::from_sort_exprs(sort_exprs.iter())
+                .inner
+                .as_slice(),
         );
         let mode = match input.execution_mode() {
             ExecutionMode::Unbounded if sort_satisfied => ExecutionMode::Unbounded,
@@ -895,7 +897,9 @@ impl ExecutionPlan for SortExec {
             .input
             .equivalence_properties()
             .ordering_satisfy_requirement(
-                PhysicalSortRequirement::from_sort_exprs(self.expr.iter()).as_slice(),
+                PhysicalSortRequirement::from_sort_exprs(self.expr.iter())
+                    .inner
+                    .as_slice(),
             );
 
         match (sort_satisfied, self.fetch.as_ref()) {