Mysqlreport 提示參數(shù)獲取錯(cuò)誤的探討

909413335

在用Mysqlreport進(jìn)行服務(wù)器性能分析的時(shí)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

打開(kāi)Mysqlreport源碼，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沒(méi)有賦值，是null。猜測(cè)，沒(méi)有證實(shí)。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'})

參考手冊(cè)里是這么說(shuō)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后不默認(rèn)提供這個(gè)參數(shù)了。除非編譯的時(shí)候強(qiáng)制指定。我安裝的是5.1.56 rpm 包，plugin innodb，所以沒(méi)有這個(gè)參數(shù)。

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'})

手冊(cè)里是這么說(shuō)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。所以提示找不到這個(gè)參數(shù)。

上面的提示信息都是正常的，某些參數(shù)MYSQL里沒(méi)有提供了，但是Mysqlreport進(jìn)行了檢測(cè)。