2 files changed, 36 insertions, 0 deletions
diff --git a/src/test/regress/expected/case.out b/src/test/regress/expected/case.out
index 7fcfe9a7a60..f5136c17abb 100644
--- a/src/test/regress/expected/case.out
+++ b/src/test/regress/expected/case.out
@@ -263,6 +263,31 @@ SELECT *
  4 |   | 2 | -4
 (2 rows)
 
+-- Tests for constant subexpression simplification
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, 2) = 2;
+        QUERY PLAN        
+--------------------------
+ Result
+   One-Time Filter: false
+(2 rows)
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, 1) IS NOT NULL;
+        QUERY PLAN        
+--------------------------
+ Result
+   One-Time Filter: false
+(2 rows)
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, null) = 2;
+        QUERY PLAN        
+--------------------------
+ Result
+   One-Time Filter: false
+(2 rows)
+
 --
 -- Examples of updates involving tables
 --
diff --git a/src/test/regress/sql/case.sql b/src/test/regress/sql/case.sql
index 0655d266f60..83fe43be6b8 100644
--- a/src/test/regress/sql/case.sql
+++ b/src/test/regress/sql/case.sql
@@ -137,6 +137,17 @@ SELECT *
   FROM CASE_TBL a, CASE2_TBL b
   WHERE COALESCE(f,b.i) = 2;
 
+-- Tests for constant subexpression simplification
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, 2) = 2;
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, 1) IS NOT NULL;
+
+explain (costs off)
+SELECT * FROM CASE_TBL WHERE NULLIF(1, null) = 2;
+
 --
 -- Examples of updates involving tables
 --