mysql查看索引的大小

1 ，show table status from your_database_name  这个不准；

2，这个比较详细
select
database_name,
table_name,
index_name,
round((stat_value*@@innodb_page_size)/1024/1024, 2) SizeMB,
round(((100/(SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES t WHERE t.TABLE_NAME = iis.table_name and t.TABLE_SCHEMA = iis.database_name))*(stat_value*@@innodb_page_size)), 2) `Percentage`
from mysql.innodb_index_stats iis
where stat_name='size'
and table_name = 'your_table'
and database_name = 'your_database_name'