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Hit ratio

Hit ratio
Hit ratio Histogram
First vertical bar
A buffer cache size of 5,000 results in a hit ratio of 0.60.
Second vertical barIncreasing the cache size to 6,000 buffers yields a large increase in the hit ratio, which is now 0.80.
Third vertical bar Going up to 7,000 buffers yields a smaller increase, and the hit ratio is now 0.90.
Fourth vertical bar Further increasing the cache to 8,000 buffers yields an even smaller increase, taking the hit ratio to 0.95.
Fifth vertical barIncreasing the cache from 8,000 to 9,000 buffers results in no increase to the hit ratio. You should undo this change and run with an 8,000 buffer cache.