diff --git a/tests/pytest/query/unionAllTest.py b/tests/pytest/query/unionAllTest.py
index 9a7aedc763db05ebb11da33dc65fa74b2ba8daa3..eaef5d2d573ba3c0ab08ed7ede991d25913c2454 100644
--- a/tests/pytest/query/unionAllTest.py
+++ b/tests/pytest/query/unionAllTest.py
@@ -116,10 +116,41 @@ class TDTestCase:
                 sql += f"union all select last(*) from sub{i} "
 
             tdSql.execute("create table sub%d using st2 tags('nchar%d')" % (i, i))
-            tdSql.execute("insert into sub%d values(%d, %d, %d, %d)" % (i, self.ts + i, i, i, i))
+            tdSql.execute("insert into sub%d values(%d, %d, %d, %d)(%d, %d, %d, %d)" % (i, self.ts + i, i, i, i,self.ts + i + 101, i + 101, i + 101, i + 101))
 
         tdSql.error(sql)
 
+        # TS-795
+        tdLog.info("test case for TS-795")
+        
+        functions = ["*", "count", "avg", "twa", "irate", "sum", "stddev", "leastsquares", "min", "max", "first", "last", "top", "bottom", "percentile", "apercentile", "last_row"]
+        
+        for func in functions:
+            expr = func
+            if func == "top" or func == "bottom":
+                expr += "(c1, 1)"
+            elif func == "percentile" or func == "apercentile":
+                expr += "(c1, 0.5)"
+            elif func == "leastsquares":
+                expr = func + "(c1, 1, 1)"
+            elif func == "*":
+                expr = func
+            else:
+                expr += "(c1)"
+
+            for i in range(100):
+                if i == 0:
+                    sql = f"select {expr} from sub0 "
+                else:
+                    sql += f"union all select {expr} from sub{i} "
+
+            tdSql.query(sql)
+            if func == "*":
+                tdSql.checkRows(200)
+            else:
+                tdSql.checkRows(100)
+
+
     def stop(self):
         tdSql.close()
         tdLog.success("%s successfully executed" % __file__)