关于Innodb_buffer_pool_pages_latched

longxibendi

我的MySQL是5.1.45
在输入 show status ;
发现没有这一行
Innodb_buffer_pool_pages_latched    不知为什么？

horizonhyg

回复 1# longxibendi


    源代码中已经把他做成开发调试了，这个应该是不显示的
   

#ifdef UNIV_DEBUG
  {"buffer_pool_pages_latched",
  (char*) &export_vars.innodb_buffer_pool_pages_latched,  SHOW_LONG},
#endif /* UNIV_DEBUG */

longxibendi

回复 2# horizonhyg


    谢谢。

r55wen

MySQL5.1的文档上这样写：

The number of latched pages in InnoDB buffer pool. These are pages currently being read or written or that cannot be flushed
or removed for some other reason. Calculation of this variable is expensive, so as of MySQL 5.1.28, it is available only when
the UNIV_DEBUG system is defined at server build time

我的理解是：

计算这个参数消耗很多资源，所以它仅在服务建立时UNLV_DEBUG系统被定义的情况才下有效。