Com_xxx 和 handler_xxx 有什么区别？

Question

最初我的com_delete变量和handler_xxx变量为零。

| Com_delete | 0 |+ | Handler_delete | 0 | +----------------+-------+

然后我发出了一个删除查询 delete from gt where i=1;

当我检查这两个变量时，它都变成了 1。

我的问题是这些变量有何区别？我正在使用 MySQL 5.6

Answer 1

Com_delete 是用户向 MySQL 发送 DELETE 命令的次数。

Handler_delete 是 MySQL 服务器通过内部 API 向存储引擎发送删除处理程序的次数

为了说明差异，这里有一个例子：

mysql> delete from t1 where id < 100;
Query OK, 88 rows affected (0.00 sec)

mysql> show status like 'Com_delete';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Com_delete    | 1     |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show status like 'Handler_delete';
+----------------+-------+
| Variable_name  | Value |
+----------------+-------+
| Handler_delete | 88    |
+----------------+-------+
1 row in set (0.00 sec)