Test + workaround for SanityCheck plan

datafusion/core/src/physical_optimizer/sanity_checker.rs

@@ -35,6 +35,8 @@ use datafusion_physical_plan::{get_plan_string, ExecutionPlanProperties};
 
 use datafusion_physical_expr_common::sort_expr::format_physical_sort_requirement_list;
 use datafusion_physical_optimizer::PhysicalOptimizerRule;
+use datafusion_physical_plan::sorts::sort::SortExec;
+use datafusion_physical_plan::union::UnionExec;
 use itertools::izip;
 
 /// The SanityCheckPlan rule rejects the following query plans:
@@ -126,6 +128,14 @@ pub fn check_plan_sanity(
         plan.required_input_ordering().iter(),
         plan.required_input_distribution().iter()
     ) {
+        // TEMP HACK WORKAROUND https://github.com/apache/datafusion/issues/11492
+        if child.as_any().downcast_ref::<UnionExec>().is_some() {
+            continue;
+        }
+        if child.as_any().downcast_ref::<SortExec>().is_some() {
+            continue;
+        }
+
         let child_eq_props = child.equivalence_properties();
         if let Some(sort_req) = sort_req {
             if !child_eq_props.ordering_satisfy_requirement(sort_req) {

datafusion/sqllogictest/test_files/union.slt

@@ -538,6 +538,9 @@ physical_plan
 # Clean up after the test
 ########
 
+statement ok
+drop table t
+
 statement ok
 drop table t1;
 
@@ -761,3 +764,37 @@ SELECT NULL WHERE FALSE;
 ----
 0.5
 1
+
+###
+# Test for https://github.com/apache/datafusion/issues/11492
+###
+
+# Input data is
+# a,b,c
+# 1,2,3
+
+statement ok
+CREATE EXTERNAL TABLE t (
+  a INT,
+  b INT,
+  c INT
+)
+STORED AS CSV
+LOCATION '../core/tests/data/example.csv'
+WITH ORDER (a ASC)
+OPTIONS ('format.has_header' 'true');
+
+query T
+SELECT (SELECT a from t ORDER BY a) UNION ALL (SELECT 'bar' as a from t) ORDER BY a;
+----
+1
+bar
+
+query I
+SELECT (SELECT a from t ORDER BY a) UNION ALL (SELECT NULL as a from t) ORDER BY a;
+----
+1
+NULL 
+
+statement ok
+drop table t