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From Tyler Hobbs <ty...@datastax.com>
Subject Re: Combining all CFs into one big one
Date Mon, 02 May 2011 16:52:07 GMT
On Mon, May 2, 2011 at 5:05 AM, David Boxenhorn <david@taotown.com> wrote:

> Wouldn't it be the case that the once-used rows in your batch process would
> quickly be traded out of the cache, and replaced by frequently-used rows?
>

Yes, and you'll pay a cache miss penalty for each of the replacements.


> This would be the case even if your batch process goes on for a long time,
> since caching is done on a row-by-row basis. In effect, it would mean that
> part of your cache is taken up by the batch process, much as if you
> dedicated a permanent cache to the batch - except that it isn't permanent,
> so it's better!
>

Right, but we didn't want to cache any of the batch CF in the first place,
because caching that CF is worth very little.  With separate CFs, we could
explicitly give it no cache.  Now we have no control over how much of the
cache it evicts.

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