Mysqlreport 提示参数获取错误的探讨

909413335

在用Mysqlreport进行服务器性能分析的时候，提示如下信息

1. Use of uninitialized value in multiplication (*) at ./mysqlreport line 829, <STDIN> line 1.
2. Use of uninitialized value in formline at ./mysqlreport line 1227, <STDIN> line 1.
3. Use of uninitialized value in formline at ./mysqlreport line 1233, <STDIN> line 1.
4. Use of uninitialized value in formline at ./mysqlreport line 1235, <STDIN> line 1.
5. MySQL 5.1.56-community- uptime 19 15:5:26 Tue Jun 14 20:28:45 2011

打开Mysqlreport源码，找到第829行

1. 826 sub perc # Percentage
2. 827 {
3. 828 my($is, $of) = @_;
4. 829 return sprintf "%.2f", ($is * 100) / ($of ||= 1);
5. 830 }

可能$is没有赋值，是null。猜测，没有证实。再看1227行：

1. 1227$stats{'Innodb_buffer_pool_pages_latched'},perc($stats{'Innodb_buffer_pool_pages_latched'},$stats{'Innodb_buffer_pool_pages_total'})

参考手册里是这么说的：

1. Innodb_buffer_pool_pages_latched
2. 
   
3. 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.

5.1.28后不默认提供这个参数了。除非编译的时候强制指定。我安装的是5.1.56 rpm 包，plugin innodb，所以没有这个参数。

再看1233,1235行

1. 1233$stats{'Innodb_buffer_pool_read_ahead_rnd'},t($stats{'Innodb_buffer_pool_read_ahead_rnd'})
2. 1234 Ahead Sql @>>>>>>>> @>>>>>/s
3. 1235$stats{'Innodb_buffer_pool_read_ahead_seq'},t($stats{'Innodb_buffer_pool_read_ahead_seq'})

手册里是这么说的：

1. Innodb_buffer_pool_read_ahead_rnd
2. 
   
3. The number of “random” read-aheads initiated by InnoDB. This happens when a query scans a large portion of a table but in random order.
4. 
   
5. For InnoDB Plugin, this variable was removed in MySQL 5.1.41.

5.1.41后,Innodb Plugin下，removed了。所以提示找不到这个参数。

上面的提示信息都是正常的，某些参数MYSQL里没有提供了，但是Mysqlreport进行了检测。