Saturday, February 28, 2015

Sqlserver 2012 Cache Hit Ratio

Hi,


I am not sure how you are calculating BCHR but below query would give you correct value,Source



SELECT cast((CAST(A.cntr_value1 AS NUMERIC) / CAST(B.cntr_value2 AS NUMERIC))*100 as decimal(10,2)) AS Buffer_Cache_Hit_Ratio

FROM (

SELECT cntr_value AS cntr_value1

FROM sys.dm_os_performance_counters

WHERE object_name = 'SQLServer:Buffer Manager'

AND counter_name = 'Buffer cache hit ratio'

) AS A,

(

SELECT cntr_value AS cntr_value2

FROM sys.dm_os_performance_counters

WHERE object_name = 'SQLServer:Buffer Manager'

AND counter_name = 'Buffer cache hit ratio base'

) AS B



if you read the article by Jonathan it clearly says don't rely on BCHR for gauging memory pressure




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