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From Peter Schuller <>
Subject Re: flush_largest_memtables_at messages in 7.4
Date Wed, 13 Apr 2011 02:57:43 GMT
> One thing I am noticing is that cache hit rate is very low even though my
> cache key size is 1M and I have less than 1M rows. Not sure why so many
> cache miss?

The key cache should be strictly LRU for read-only workloads. For
write/read workloads it may not be strictly LRU because compaction
causes key cache migration.

In your case:

>                Key cache capacity: 1000000
>                Key cache size: 256013
>                Key cache hit rate: 0.33801452784503633

So you have only 256k in the cache. Have you run for long enough after
enabling it for it to actually be fully populated?

/ Peter Schuller

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