diff --git a/tests/pytest/random-test/random-test-multi-threading-3.py b/tests/pytest/random-test/random-test-multi-threading-3.py
index 47c4228a8fb2df18ee8e8ce8b407d3d5b3b83ac8..0c8612bc44b5d18b7ef4d699ac5c03044c9d4002 100644
--- a/tests/pytest/random-test/random-test-multi-threading-3.py
+++ b/tests/pytest/random-test/random-test-multi-threading-3.py
@@ -24,6 +24,7 @@ last_tb = ""
 last_stb = ""
 written = 0
 last_timestamp = 0
+colAdded = False
 
 
 class Test (Thread):
@@ -140,6 +141,26 @@ class Test (Thread):
             last_tb = ""
             written = 0
 
+    def alter_table_to_add_col(self):
+        tdLog.info("alter_table_to_add_col")
+        global last_stb
+        global colAdded
+
+        if last_stb != "" and colAdded == False:
+            tdSql.execute(
+                "alter table %s add column col binary(20)" %
+                last_stb)
+            colAdded = True
+
+    def alter_table_to_drop_col(self):
+        tdLog.info("alter_table_to_drop_col")
+        global last_stb
+        global colAdded
+
+        if last_stb != "" and colAdded:
+            tdSql.execute("alter table %s drop column col" % last_stb)
+            colAdded = False
+
     def restart_database(self):
         tdLog.info("restart_database")
         global last_tb
@@ -235,6 +256,8 @@ class Test (Thread):
             7: self.reset_database,
             8: self.delete_datafiles,
             9: self.drop_stable,
+            10: self.alter_table_to_add_col,
+            11: self.alter_table_to_drop_col,
         }
 
         queryOp = {
@@ -256,7 +279,7 @@ class Test (Thread):
             while True:
                 self.dbEvent.wait()
                 tdLog.notice("second thread")
-                randDbOp = random.randint(1, 9)
+                randDbOp = random.randint(1, 11)
                 dbOp.get(randDbOp, lambda: "ERROR")()
                 self.dbEvent.clear()
                 self.dataEvent.clear()
diff --git a/tests/pytest/random-test/random-test-multi-threading.py b/tests/pytest/random-test/random-test-multi-threading.py
index 65b6dcd948ca6a789d66f8c20ca3c2397bff0974..ff72aa0ea670769232e59181e554719850959ba9 100644
--- a/tests/pytest/random-test/random-test-multi-threading.py
+++ b/tests/pytest/random-test/random-test-multi-threading.py
@@ -14,6 +14,7 @@
 import sys
 import random
 import threading
+import queue
 
 from util.log import *
 from util.cases import *
@@ -24,13 +25,16 @@ last_tb = ""
 last_stb = ""
 written = 0
 last_timestamp = 0
+colAdded = False
+killed = False
 
 
 class Test (threading.Thread):
-    def __init__(self, threadId, name):
+    def __init__(self, threadId, name, q):
         threading.Thread.__init__(self)
         self.threadId = threadId
         self.name = name
+        self.q = q
 
         self.threadLock = threading.Lock()
 
@@ -38,11 +42,12 @@ class Test (threading.Thread):
         tdLog.info("create_table")
         global last_tb
         global written
+        global killed
 
         current_tb = "tb%d" % int(round(time.time() * 1000))
 
         if (current_tb == last_tb):
-            return
+            return 0
         else:
             tdLog.info("will create table %s" % current_tb)
 
@@ -52,8 +57,14 @@ class Test (threading.Thread):
                     current_tb)
                 last_tb = current_tb
                 written = 0
+                killed = False
             except Exception as e:
-                tdLog.info(repr(e))
+                tdLog.info("killed: %d error: %s" % (killed, e.args[0]))
+                if killed and (e.args[0] == 'network unavailable'):
+                    tdLog.info("database killed, expect failed")
+                    return 0
+                return -1
+        return 0
 
     def insert_data(self):
         tdLog.info("insert_data")
@@ -75,22 +86,34 @@ class Test (threading.Thread):
             for j in range(0, insertRows):
                 if (last_tb == ""):
                     tdLog.info("no table, return")
-                    return
-                tdSql.execute(
-                    'insert into %s values (%d + %da, %d, "test")' %
-                    (last_tb, start_time, last_timestamp, last_timestamp))
-                written = written + 1
-                last_timestamp = last_timestamp + 1
+                    return 0
+
+                try:
+                    tdSql.execute(
+                        'insert into %s values (%d + %da, %d, "test")' %
+                        (last_tb, start_time, last_timestamp, last_timestamp))
+                    written = written + 1
+                    last_timestamp = last_timestamp + 1
+                except Exception as e:
+                    if killed:
+                        tdLog.info(
+                            "database killed, expect failed %s" %
+                            e.args[0])
+                        return 0
+                    tdLog.info(repr(e))
+                    return -1
+        return 0
 
     def query_data(self):
         tdLog.info("query_data")
         global last_tb
-        global written
+        global killed
 
-        if (written > 0):
+        if not killed and last_tb != "":
             tdLog.info("query data from table")
             tdSql.query("select * from %s" % last_tb)
             tdSql.checkRows(written)
+        return 0
 
     def create_stable(self):
         tdLog.info("create_stable")
@@ -101,9 +124,7 @@ class Test (threading.Thread):
 
         current_stb = "stb%d" % int(round(time.time() * 1000))
 
-        if (current_stb == last_stb):
-            return
-        else:
+        if (current_stb != last_stb):
             tdLog.info("will create stable %s" % current_stb)
             tdLog.info(
                 'create table %s(ts timestamp, c1 int, c2 nchar(10)) tags (t1 int, t2 nchar(10))' %
@@ -131,6 +152,8 @@ class Test (threading.Thread):
             written = written + 1
             last_timestamp = last_timestamp + 1
 
+        return 0
+
     def drop_stable(self):
         tdLog.info("drop_stable")
         global last_stb
@@ -139,31 +162,63 @@ class Test (threading.Thread):
 
         if (last_stb == ""):
             tdLog.info("no super table")
-            return
         else:
-            tdLog.info("will drop last super table")
+            tdLog.info("will drop last super table %s" % last_stb)
             tdSql.execute('drop table %s' % last_stb)
             last_stb = ""
             last_tb = ""
             written = 0
+        return 0
+
+    def alter_table_to_add_col(self):
+        tdLog.info("alter_table_to_add_col")
+        global last_stb
+        global colAdded
+
+        if last_stb != "" and colAdded == False:
+            tdSql.execute(
+                "alter table %s add column col binary(20)" %
+                last_stb)
+            colAdded = True
+        return 0
+
+    def alter_table_to_drop_col(self):
+        tdLog.info("alter_table_to_drop_col")
+        global last_stb
+        global colAdded
+
+        if last_stb != "" and not colAdded:
+            tdSql.execute("alter table %s drop column col" % last_stb)
+            colAdded = False
+        return 0
 
     def restart_database(self):
         tdLog.info("restart_database")
         global last_tb
         global written
+        global killed
 
         tdDnodes.stop(1)
+        killed = True
         tdDnodes.start(1)
-#        tdLog.sleep(5)
+        tdLog.sleep(10)
+        killed = False
+        return 0
 
     def force_restart_database(self):
         tdLog.info("force_restart_database")
         global last_tb
         global written
+        global killed
 
         tdDnodes.forcestop(1)
+        last_tb = ""
+        written = 0
+        killed = True
         tdDnodes.start(1)
 #        tdLog.sleep(10)
+        killed = False
+        return 0
 
     def drop_table(self):
         tdLog.info("drop_table")
@@ -176,6 +231,7 @@ class Test (threading.Thread):
                 tdSql.execute("drop table %s" % last_tb)
                 last_tb = ""
                 written = 0
+        return 0
 
     def query_data_from_stable(self):
         tdLog.info("query_data_from_stable")
@@ -183,10 +239,10 @@ class Test (threading.Thread):
 
         if (last_stb == ""):
             tdLog.info("no super table")
-            return
         else:
             tdLog.info("will query data from super table")
             tdSql.execute('select * from %s' % last_stb)
+        return 0
 
     def reset_query_cache(self):
         tdLog.info("reset_query_cache")
@@ -196,38 +252,44 @@ class Test (threading.Thread):
         tdLog.info("reset query cache")
         tdSql.execute("reset query cache")
 #        tdLog.sleep(1)
+        return 0
 
     def reset_database(self):
         tdLog.info("reset_database")
         global last_tb
         global last_stb
         global written
+        global killed
 
         tdDnodes.forcestop(1)
+        killed = True
         tdDnodes.deploy(1)
         tdDnodes.start(1)
         tdSql.prepare()
-        last_tb = ""
-        last_stb = ""
-        written = 0
+        killed = False
+        return 0
 
     def delete_datafiles(self):
         tdLog.info("delete_data_files")
         global last_tb
         global last_stb
         global written
+        global killed
 
         dnodesDir = tdDnodes.getDnodesRootDir()
         tdDnodes.forcestop(1)
         dataDir = dnodesDir + '/dnode1/data/*'
         deleteCmd = 'rm -rf %s' % dataDir
         os.system(deleteCmd)
-
-        tdDnodes.start(1)
-        tdSql.prepare()
         last_tb = ""
         last_stb = ""
         written = 0
+        killed = True
+
+        tdDnodes.start(1)
+        tdSql.prepare()
+        killed = False
+        return 0
 
     def run(self):
         dataOp = {
@@ -246,6 +308,8 @@ class Test (threading.Thread):
             7: self.reset_database,
             8: self.delete_datafiles,
             9: self.drop_stable,
+            10: self.alter_table_to_add_col,
+            11: self.alter_table_to_drop_col,
         }
 
         if (self.threadId == 1):
@@ -253,16 +317,38 @@ class Test (threading.Thread):
                 self.threadLock.acquire()
                 tdLog.notice("first thread")
                 randDataOp = random.randint(1, 3)
-                dataOp.get(randDataOp, lambda: "ERROR")()
-                self.threadLock.release()
+                ret1 = dataOp.get(randDataOp, lambda: "ERROR")()
+
+                if ret1 == -1:
+                    self.q.put(-1)
+                    tdLog.exit("first thread failed")
+                else:
+                    self.q.put(1)
+
+                if (self.q.get() != -2):
+                    self.threadLock.release()
+                else:
+                    self.q.put(-1)
+                    tdLog.exit("second thread failed, first thread exit too")
 
         elif (self.threadId == 2):
             while True:
-                tdLog.notice("second thread")
                 self.threadLock.acquire()
-                randDbOp = random.randint(1, 9)
-                dbOp.get(randDbOp, lambda: "ERROR")()
-                self.threadLock.release()
+                tdLog.notice("second thread")
+                randDbOp = random.randint(1, 11)
+                ret2 = dbOp.get(randDbOp, lambda: "ERROR")()
+
+                if ret2 == -1:
+                    self.q.put(-2)
+                    tdLog.exit("second thread failed")
+                else:
+                    self.q.put(2)
+
+                if (self.q.get() != -1):
+                    self.threadLock.release()
+                else:
+                    self.q.put(-2)
+                    tdLog.exit("first thread failed, second exit too")
 
 
 class TDTestCase:
@@ -273,14 +359,19 @@ class TDTestCase:
     def run(self):
         tdSql.prepare()
 
-        test1 = Test(1, "data operation")
-        test2 = Test(2, "db operation")
+        q = queue.Queue()
+        test1 = Test(1, "data operation", q)
+        test2 = Test(2, "db operation", q)
 
         test1.start()
         test2.start()
         test1.join()
         test2.join()
 
+        while not q.empty():
+            if (q.get() != 0):
+                tdLog.exit("failed to end of test")
+
         tdLog.info("end of test")
 
     def stop(self):
diff --git a/tests/pytest/stable/query_after_reset.py b/tests/pytest/stable/query_after_reset.py
index 2bc171ae5d53af86bb72b142ba54b52c76a9e80c..61f6558b83b95333bf37f1c0df13c3cf8c43d8cb 100644
--- a/tests/pytest/stable/query_after_reset.py
+++ b/tests/pytest/stable/query_after_reset.py
@@ -126,7 +126,7 @@ class Test:
     def delete_datafiles(self):
         tdLog.info("delete data files")
         dnodesDir = tdDnodes.getDnodesRootDir()
-        dataDir = dnodesDir + '/dnode1/*'
+        dataDir = dnodesDir + '/dnode1/data/*'
         deleteCmd = 'rm -rf %s' % dataDir
         os.system(deleteCmd)
 
diff --git a/tests/pytest/util/sql.py b/tests/pytest/util/sql.py
index 3b86a5334396f65b6a5a0f0685403560f3e14499..e282298b7c0dafded323215a2b324cf77d554948 100644
--- a/tests/pytest/util/sql.py
+++ b/tests/pytest/util/sql.py
@@ -41,16 +41,12 @@ class TDSql:
     def prepare(self):
         tdLog.info("prepare database:db")
         s = 'reset query cache'
-        print(s)
         self.cursor.execute(s)
         s = 'drop database if exists db'
-        print(s)
         self.cursor.execute(s)
         s = 'create database db'
-        print(s)
         self.cursor.execute(s)
         s = 'use db'
-        print(s)
         self.cursor.execute(s)
 
     def error(self, sql):
@@ -74,7 +70,6 @@ class TDSql:
 
     def query(self, sql):
         self.sql = sql
-        print(sql)
         self.cursor.execute(sql)
         self.queryResult = self.cursor.fetchall()
         self.queryRows = len(self.queryResult)
@@ -191,7 +186,6 @@ class TDSql:
 
     def execute(self, sql):
         self.sql = sql
-        print(sql)
         self.affectedRows = self.cursor.execute(sql)
         return self.affectedRows