Simplify unchanged case

Author: Shiv Bhatia

datafusion/optimizer/src/push_down_filter.rs

@@ -836,11 +836,8 @@ impl OptimizerRule for PushDownFilter {
                 // it would change semantics: the limit should apply before
                 // the filter, not after.
                 if sort.fetch.is_some() {
-                    let plan = LogicalPlan::Filter(Filter::try_new(
-                        filter.predicate,
-                        Arc::new(LogicalPlan::Sort(sort)),
-                    )?);
-                    return Ok(Transformed::no(plan));
+                    filter.input = Arc::new(LogicalPlan::Sort(sort));
+                    return Ok(Transformed::no(LogicalPlan::Filter(filter)));
                 }
                 let new_filter =
                     Filter::try_new(filter.predicate, Arc::clone(&sort.input))
@@ -1144,11 +1141,8 @@ impl OptimizerRule for PushDownFilter {
                 // would change semantics: the limit should apply before the
                 // filter, not after.
                 if scan.fetch.is_some() {
-                    let plan = LogicalPlan::Filter(Filter::try_new(
-                        filter.predicate,
-                        Arc::new(LogicalPlan::TableScan(scan)),
-                    )?);
-                    return Ok(Transformed::no(plan));
+                    filter.input = Arc::new(LogicalPlan::TableScan(scan));
+                    return Ok(Transformed::no(LogicalPlan::Filter(filter)));
                 }
                 let filter_predicates = split_conjunction(&filter.predicate);