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From Benson Margulies <>
Subject Re: Replacing Redis
Date Sun, 20 Feb 2011 14:04:06 GMT
Thanks for replying, but it is not at all clear to me that redis was
ever the right solution to the problem at hand. I'm still working out
whether, in fact, Cassandra is.

Up to a fairly large scale, this particular problem needs no 'cache'
at all. It needs a write-behind persistence mechanism -- a log. The
simplest form of which is, of course, just a file, though that
solution poses problems for backup and some failure scenarios.

There are two parts to the data footprint, one growing more rapidly
than the other. The faster growing part has a natural 'redis-friendly'
data model (keys map to values); but it would map to EHCache as well.
However, the initial redis/jredis implementation used redis, rather
than local ordinary JVM objects, for the slower growing part. The
lpush/ltrim usage was in here.

At really gigantic scales, which I don't claim to have entirely
thought through, even the slow-growing part will stop fitting into
memory. However, it has a natural architecture for distribution, so
there is a dilemma in my head between following the logic of the
algorithm out to implement distribution, or letting something like
cassandra do that for me.

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