mysql 5.6中sql语句统计每个索引的具体情况
http://aadant.com/blog/2014/02/04/how-to-calculate-a-specific-innodb-index-size/
在 mysql中 ，使用
show table status like '表名'\G;可以看出具体表的情况，比如：
Name: t
Engine: InnoDB
Version: 10
Row_format: Compact
Rows: 4186170
Avg_row_length: 34
Data_length: 143310848
Max_data_length: 0
Index_length: 146030592
Data_free: 6291456
Auto_increment: NULL
Create_time: 2014-02-04 15:40:54
Update_time: NULL
Check_time: NULL
Collation: latin1_swedish_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
其中可以看出Data_length和Index_length，显示的是索引段的总的大小，那么一个表中如果有多个索引，要如何查看某个索引的大小，页呢？可以使用SQL语句完成，但要先分析下表，步骤如下：
ANALYZE table t;SELECT sum(stat_value) pages, index_name, sum(stat_value) * @@innodb_page_size sizeFROM mysql.innodb_index_statsWHERE table_name = 't' AND database_name = 'test' AND stat_description = 'Number of pages in the index'GROUP BY index_name;+-------+-----------------+-----------+| pages | index_name????? | size????? |+-------+-----------------+-----------+|? 8747 | GEN_CLUST_INDEX | 143310848 ||? 4456 | a?????????????? |? 73007104 ||? 4457 | b?????????????? |? 73023488 |+-------+-----------------+-----------+3 rows in set (0.00 sec)
