test: demonstrate bug where the SanityCheckPlan does not know to igno…

…re constant columns in sort

datafusion/sqllogictest/test_files/order.slt

@@ -1196,3 +1196,36 @@ physical_plan
 02)--RepartitionExec: partitioning=RoundRobinBatch(2), input_partitions=1
 03)----SortExec: TopK(fetch=1), expr=[a@0 ASC NULLS LAST], preserve_partitioning=[false]
 04)------CsvExec: file_groups={1 group: [[WORKSPACE_ROOT/datafusion/core/tests/data/window_2.csv]]}, projection=[a, b], has_header=true
+
+
+# Test: inputs into union with different orderings
+query TT
+explain select * from (select b, c, a, NULL::int as a0 from ordered_table order by a, c) t1
+union all
+select * from (select b, c, NULL::int as a, a0 from ordered_table order by a0, c) t2
+order by d, c, a, a0, b
+limit 2;
+----
+logical_plan
+01)Projection: t1.b, t1.c, t1.a, t1.a0
+02)--Sort: t1.d ASC NULLS LAST, t1.c ASC NULLS LAST, t1.a ASC NULLS LAST, t1.a0 ASC NULLS LAST, t1.b ASC NULLS LAST, fetch=2
+03)----Union
+04)------SubqueryAlias: t1
+05)--------Projection: ordered_table.b, ordered_table.c, ordered_table.a, Int32(NULL) AS a0, ordered_table.d
+06)----------TableScan: ordered_table projection=[a, b, c, d]
+07)------SubqueryAlias: t2
+08)--------Projection: ordered_table.b, ordered_table.c, Int32(NULL) AS a, ordered_table.a0, ordered_table.d
+09)----------TableScan: ordered_table projection=[a0, b, c, d]
+
+# Test: run the query from above
+# TODO: query fails since the constant columns t1.a0 and t2.a are not in the ORDER BY subquery,
+# and SanityCheckPlan does not allow this.
+statement error DataFusion error: SanityCheckPlan
+select * from (select b, c, a, NULL::int as a0 from ordered_table order by a, c) t1
+union all
+select * from (select b, c, NULL::int as a, a0 from ordered_table order by a0, c) t2
+order by d, c, a, a0, b
+limit 2;
+
+statement ok
+drop table ordered_table;