diff --git a/library/think/Model.php b/library/think/Model.php
index af278982..cb04724c 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -293,6 +293,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
             return false;
         }
 
+        $db = self::db();
         if ($this->isUpdate) {
             // 自动更新
             $this->autoCompleteData($this->update);
@@ -320,7 +321,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
                 }
             }
 
-            $result = self::db()->where($where)->update($data);
+            $result = $db->where($where)->update($data);
 
             // 更新回调
             $this->trigger('after_update', $this);
@@ -332,11 +333,11 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
                 return false;
             }
 
-            $result = self::db()->insert($this->data);
+            $result = $db->insert($this->data);
 
             // 获取自动增长主键
             if ($result && $getId) {
-                $insertId = self::db()->getLastInsID();
+                $insertId = $db->getLastInsID();
                 $pk       = $this->getPk();
                 if (is_string($pk) && $insertId) {
                     $this->data[$pk] = $insertId;
diff --git a/library/think/db/Connection.php b/library/think/db/Connection.php
index 71d84f3a..5b2ad454 100644
--- a/library/think/db/Connection.php
+++ b/library/think/db/Connection.php
@@ -506,13 +506,14 @@ abstract class Connection
      */
     public function transaction($callback)
     {
-        $this->startTrans(NOW_TIME);
+        $label = microtime(true);
+        $this->startTrans($label);
         try {
             $result = null;
             if (is_callable($callback)) {
                 $result = call_user_func_array($callback, []);
             }
-            $this->commit(NOW_TIME);
+            $this->commit($label);
             return $result;
         } catch (\PDOException $e) {
             $this->rollback();
diff --git a/library/think/model/Merge.php b/library/think/model/Merge.php
index 7cf43fb4..4b1cd0c8 100644
--- a/library/think/model/Merge.php
+++ b/library/think/model/Merge.php
@@ -166,7 +166,8 @@ class Merge extends Model
         // 处理模型数据
         $data = $this->parseData($this->name, $this->data);
 
-        self::db()->startTrans();
+        $db = self::db();
+        $db->startTrans('merge_save_' . $this->name);
         try {
             if ($this->isUpdate) {
                 // 自动写入
@@ -177,15 +178,15 @@ class Merge extends Model
                 }
 
                 // 写入主表数据
-                $result = self::db()->strict(false)->update($data);
+                $result = $db->strict(false)->update($data);
 
                 // 写入附表数据
                 foreach (static::$relationModel as $key => $model) {
                     $name  = is_int($key) ? $model : $key;
-                    $table = is_int($key) ? self::db()->getTable($model) : $model;
+                    $table = is_int($key) ? $db->getTable($model) : $model;
                     // 处理关联模型数据
                     $data  = $this->parseData($name, $this->data);
-                    $query = clone self::db();
+                    $query = clone $db;
                     $query->table($table)->strict(false)->where($this->fk, $this->data[$this->getPk()])->update($data);
                 }
                 // 新增回调
@@ -199,19 +200,19 @@ class Merge extends Model
                 }
 
                 // 写入主表数据
-                $result = self::db()->name($this->name)->strict(false)->insert($this->data);
+                $result = $db->name($this->name)->strict(false)->insert($this->data);
                 if ($result) {
-                    $insertId = self::db()->getLastInsID();
+                    $insertId = $db->getLastInsID();
                     // 写入外键数据
                     $this->data[$this->fk] = $insertId;
 
                     // 写入附表数据
                     foreach (static::$relationModel as $key => $model) {
                         $name  = is_int($key) ? $model : $key;
-                        $table = is_int($key) ? self::db()->getTable($model) : $model;
+                        $table = is_int($key) ? $db->getTable($model) : $model;
                         // 处理关联模型数据
                         $data  = $this->parseData($name, $this->data, true);
-                        $query = clone self::db();
+                        $query = clone $db;
                         $query->table($table)->strict(false)->insert($data);
                     }
                     $result = $insertId;
@@ -219,10 +220,10 @@ class Merge extends Model
                 // 新增回调
                 $this->trigger('after_insert', $this);
             }
-            self::db()->commit();
+            $db->commit('merge_save_' . $this->name);
             return $result;
         } catch (\PDOException $e) {
-            self::db()->rollback();
+            $db->rollback();
             return false;
         }
     }
@@ -237,25 +238,26 @@ class Merge extends Model
         if (false === $this->trigger('before_delete', $this)) {
             return false;
         }
-        self::db()->startTrans();
+        $db = self::db();
+        $db->startTrans('merge_delete_' . $this->name);
         try {
-            $result = self::db()->delete($this->data);
+            $result = $db->delete($this->data);
             if ($result) {
                 // 获取主键数据
                 $pk = $this->data[$this->getPk()];
 
                 // 删除关联数据
                 foreach (static::$relationModel as $key => $model) {
-                    $table = is_int($key) ? self::db()->getTable($model) : $model;
-                    $query = clone self::db();
+                    $table = is_int($key) ? $db->getTable($model) : $model;
+                    $query = clone $db;
                     $query->table($table)->where($this->fk, $pk)->delete();
                 }
             }
             $this->trigger('after_delete', $this);
-            self::db()->commit();
+            $db->commit('merge_delete_' . $this->name);
             return $result;
         } catch (\PDOException $e) {
-            self::db()->rollback();
+            $db->rollback();
             return false;
         }
     }