diff --git a/tests/pytest/query/queryGroupTbname.py b/tests/pytest/query/queryGroupTbname.py
index 095feed52fa7c44e2dd1b98a5f15c7034165b95e..73ee5f0fa8d2f358e34bab3336d6f64364b6af83 100644
--- a/tests/pytest/query/queryGroupTbname.py
+++ b/tests/pytest/query/queryGroupTbname.py
@@ -14,6 +14,7 @@ from util.log import tdLog
 from util.cases import tdCases
 from util.sql import tdSql
 from util.common import tdCom
+import random
 
 class TDTestCase:
     def init(self, conn, logSql):
@@ -47,6 +48,26 @@ class TDTestCase:
         for i in range(100):
             tdSql.query(f'select {table_name_sub1},{table_name_sub2},{table_name_sub3},{table_name_sub4},{table_name_sub5},{table_name_sub6},{table_name_sub7},{table_name_sub8},{table_name_sub9} from {table_name} where tbname in ("{table_name_sub1}","{table_name_sub2}","{table_name_sub3}","{table_name_sub4}","{table_name_sub5}","{table_name_sub6}","{table_name_sub7}","{table_name_sub8}","{table_name_sub9}") and ts >= "1980-01-01 00:00:00.000"')
             tdSql.checkRows(90)
+        
+        # TS-634
+        tdLog.info("test case for bug TS-634")
+        tdSql.execute("create database test")
+        tdSql.execute("use test")
+        tdSql.execute("create table meters (ts TIMESTAMP,voltage INT) TAGS (tableid INT)")
+        tdSql.execute("CREATE TABLE t1 USING meters TAGS (1)")
+        tdSql.execute("CREATE TABLE t2 USING meters TAGS (2)")
+
+        ts = 1605381041000
+        for i in range(10):                
+            tdSql.execute("INSERT INTO t1 values(%d, %d)" % (ts + i, random.randint(0, 100)))
+            tdSql.execute("INSERT INTO t2 values(%d, %d)" % (ts + i, random.randint(0, 100)))
+        
+        tdSql.query("select last_row(*), tbname from meters group by tbname order by ts desc")
+        tdSql.checkRows(2)
+
+        tdSql.execute("INSERT INTO t2 values(now, 2)")
+        tdSql.query("select last_row(*), tbname from meters group by tbname order by ts desc")
+        tdSql.checkRows(2)
 
     def run(self):
         tdSql.prepare()