如何确定mysql索引是否完全适合内存

Is there a way to determine whether a mysql index fits entirely in available memory? If so, how would I:

• 确定 mysql 索引的大小
• 确定应用程序的可用内存
• 确定索引是否完全适合内存

推荐答案

取决于存储引擎

SELECT FLOOR(SUM(index_length)/POWER(1024,2)) IndexSizesMB
FROM information_schema.tables WHERE engine='MyISAM' AND
table_schema NOT IN ('information_schema','performance_schema','mysql');

从key_buffer_size 中减去它.如果答案>0，然后是

SELECT FLOOR(SUM(data_length+index_length)/POWER(1024,2)) InnoDBSizeMB
FROM information_schema.tables WHERE engine='InnoDB';