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From Peter Schuller <>
Subject Re: keycache persisted to disk ?
Date Mon, 13 Feb 2012 08:49:48 GMT
> I'm making an assumption . . .  I don't yet know enough about cassandra to
> prove they are in the cache. I have my keycache set to 2 million, and am
> only querying ~900,000 keys. so after the first time I'm assuming they are
> in the cache.

Note that the key cache only caches the index positions in the data
file, and not the actual data. The key cache will only ever eliminate
the I/O that would have been required to lookup the index entry; it
doesn't help to eliminate seeking to get the data (but as usual, it
may still be in the operating system page cache).

/ Peter Schuller (@scode,

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