[Minor], Bug Fix: Add empty ordering check at the source. (#7230)

* Bug fix: Add empty ordering check during projection at the source.

* Minor changes

Author: mustafasrepo

datafusion/core/src/datasource/physical_plan/mod.rs

@@ -959,7 +959,11 @@ fn get_projected_output_ordering(
             // since rest of the orderings are violated
             break;
         }
-        all_orderings.push(new_ordering);
+        // do not push empty entries
+        // otherwise we may have `Some(vec![])` at the output ordering.
+        if !new_ordering.is_empty() {
+            all_orderings.push(new_ordering);
+        }
     }
     all_orderings
 }

datafusion/core/tests/sqllogictests/test_files/groupby.slt

@@ -3459,3 +3459,14 @@ AggregateExec: mode=Final, gby=[], aggr=[FIRST_VALUE(foo.x)]
 --CoalescePartitionsExec
 ----AggregateExec: mode=Partial, gby=[], aggr=[FIRST_VALUE(foo.x)]
 ------MemoryExec: partitions=8, partition_sizes=[1, 0, 0, 0, 0, 0, 0, 0]
+
+
+query TT
+EXPLAIN SELECT c
+FROM multiple_ordered_table
+ORDER BY c ASC;
+----
+logical_plan
+Sort: multiple_ordered_table.c ASC NULLS LAST
+--TableScan: multiple_ordered_table projection=[c]
+physical_plan CsvExec: file_groups={1 group: [[WORKSPACE_ROOT/datafusion/core/tests/data/window_2.csv]]}, projection=[c], output_ordering=[c@0 ASC NULLS LAST], has_header=true