diff --git a/src/client.h b/src/client.h
index 81ea37da0..c1311868e 100644
--- a/src/client.h
+++ b/src/client.h
@@ -181,7 +181,6 @@ class PClient : public std::enable_shared_from_this<PClient>, public CmdRes {
   // e.g：["set","key","value"]
   std::span<std::string> argv_;
   std::vector<std::string> keys_;
-  std::vector<std::pair<std::string, std::string>> kvs_;
 
  private:
   std::shared_ptr<TcpConnection> getTcpConnection() const { return tcp_connection_.lock(); }
diff --git a/src/cmd_kv.cc b/src/cmd_kv.cc
index 2a1f2a974..12c38eb8d 100644
--- a/src/cmd_kv.cc
+++ b/src/cmd_kv.cc
@@ -65,16 +65,16 @@ void AppendCmd::DoCmd(PClient* client) {
       PSTORE.ClearExpire(client->argv_[1]);  // clear key's old ttl
       PSTORE.SetValue(client->argv_[1], PObject::CreateString(client->argv_[2]));
       client->AppendInteger(static_cast<int64_t>(client->argv_[2].size()));
-    } else {  // append string
-      auto str = GetDecodedString(value);
-      std::string old_value(str->c_str(), str->size());
-      std::string new_value = old_value + client->argv_[2];
-      PSTORE.SetValue(client->argv_[1], PObject::CreateString(new_value));
-      client->AppendInteger(static_cast<int64_t>(new_value.size()));
+    } else {
+      client->SetRes(CmdRes::kErrOther, "append cmd error");
     }
-  } else {
-    client->SetRes(CmdRes::kErrOther, "append cmd error");
+    return;
   }
+  auto str = GetDecodedString(value);
+  std::string old_value(str->c_str(), str->size());
+  std::string new_value = old_value + client->argv_[2];
+  PSTORE.SetValue(client->argv_[1], PObject::CreateString(new_value));
+  client->AppendInteger(static_cast<int64_t>(new_value.size()));
 }
 
 GetsetCmd::GetsetCmd(const std::string& name, int16_t arity)
@@ -93,15 +93,15 @@ void GetsetCmd::DoCmd(PClient* client) {
       PSTORE.ClearExpire(client->argv_[1]);  // clear key's old ttl
       PSTORE.SetValue(client->argv_[1], PObject::CreateString(client->argv_[2]));
       client->AppendString("");
-    } else {  // set new value
-      auto str = GetDecodedString(old_value);
-      std::string ret_value(str->c_str(), str->size());
-      PSTORE.SetValue(client->argv_[1], PObject::CreateString(client->argv_[2]));
-      client->AppendString(ret_value);
+    } else {
+      client->SetRes(CmdRes::kErrOther, "getset cmd error");
     }
-  } else {
-    client->SetRes(CmdRes::kErrOther, "getset cmd error");
+    return;
   }
+  auto str = GetDecodedString(old_value);
+  std::string ret_value(str->c_str(), str->size());
+  PSTORE.SetValue(client->argv_[1], PObject::CreateString(client->argv_[2]));
+  client->AppendString(ret_value);
 }
 
 MgetCmd::MgetCmd(const std::string& name, int16_t arity)
@@ -121,7 +121,7 @@ void MgetCmd::DoCmd(PClient* client) {
     PObject* value;
     PError err = PSTORE.GetValueByType(k, value, PType_string);
     if (err == PError_notExist) {
-      client->AppendContent("$-1");
+      client->AppendStringLen(-1);
     } else {
       auto str = GetDecodedString(value);
       std::string reply(str->c_str(), str->size());
@@ -139,18 +139,19 @@ bool MSetCmd::DoInitial(PClient* client) {
     client->SetRes(CmdRes::kWrongNum, kCmdNameMset);
     return false;
   }
-  client->kvs_.clear();
+  client->keys_.clear();
   for (size_t index = 1; index != argcSize; index += 2) {
-    client->kvs_.emplace_back(client->argv_[index], client->argv_[index + 1]);
+    client->keys_.emplace_back(client->argv_[index]);
   }
   return true;
 }
 
 void MSetCmd::DoCmd(PClient* client) {
-  std::vector<std::pair<std::string, std::string>>::const_iterator it;
-  for (it = client->kvs_.begin(); it != client->kvs_.end(); it++) {
-    PSTORE.ClearExpire(it->first);  // clear key's old ttl
-    PSTORE.SetValue(it->first, PObject::CreateString(it->second));
+  int valueIndex = 2;
+  for (const auto& it : client->keys_) {
+    PSTORE.ClearExpire(it);  // clear key's old ttl
+    PSTORE.SetValue(it, PObject::CreateString(client->argv_[valueIndex]));
+    valueIndex += 2;
   }
   client->SetRes(CmdRes::kOk);
 }
diff --git a/src/cmd_table_manager.cc b/src/cmd_table_manager.cc
index c5f024d6c..0a03d54d6 100644
--- a/src/cmd_table_manager.cc
+++ b/src/cmd_table_manager.cc
@@ -32,7 +32,7 @@ void CmdTableManager::InitCmdTable() {
   cmds_->insert(std::make_pair(kCmdNameGet, std::move(getPtr)));
   std::unique_ptr<BaseCmd> setPtr = std::make_unique<SetCmd>(kCmdNameSet, -3);
   cmds_->insert(std::make_pair(kCmdNameSet, std::move(setPtr)));
-  std::unique_ptr<BaseCmd> appendPtr = std::make_unique<AppendCmd>(kCmdNameAppend, -3);
+  std::unique_ptr<BaseCmd> appendPtr = std::make_unique<AppendCmd>(kCmdNameAppend, 3);
   cmds_->insert(std::make_pair(kCmdNameAppend, std::move(appendPtr)));
   std::unique_ptr<BaseCmd> getsetPtr = std::make_unique<GetsetCmd>(kCmdNameGetset, 3);
   cmds_->insert(std::make_pair(kCmdNameGetset, std::move(getsetPtr)));