boof poolm命中率计算方法

SELECT  

   (D.B/(D.B + C.A))  * 100 AS bufferPoolHitRate

FROM  

   (SELECT variable_value AS A FROM performance_schema.GLOBAL_STATUS WHERE variable_name = 'innodb_buffer_pool_reads') AS C,

   (SELECT variable_value AS B FROM performance_schema.GLOBAL_STATUS WHERE variable_name = 'innodb_buffer_pool_read_requests') AS D;