[TS-715]<fix>: added test case

tests/pytest/query/unionAllTest.py

@@ -103,6 +103,29 @@ class TDTestCase:
                     select count(*) as count, loc from st where ts between 1600000000000 and 1600000000010 group by loc''')
         tdSql.checkRows(6)
 
+        # https://jira.taosdata.com:18080/browse/TS-715
+        tdLog.info("test case for TS-715")
+        sql = ""
+
+        tdSql.execute("create table st2(ts timestamp, c1 int, c2 int, c3 int) tags(loc nchar(20))")
+
+        for i in range(7000):
+            if i == 0:
+                sql = "select last(*) from sub0 "
+            else:
+                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))
+
+        exception = "Exception(\"ProgrammingError('Result set too large to be output', -2147483097)\")"
+        try:
+            tdSql.query(sql)
+        except Exception as e:
+            if {exception} != {repr(e)}:
+                tdLog.info(f"sql: {sql}, {exception} expected, actually raises {repr(e)}")
+                raise e
+
     def stop(self):
         tdSql.close()
         tdLog.success("%s successfully executed" % __file__)