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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: cassandra vs hbase summary (was facebook messaging)
Date Mon, 22 Nov 2010 21:26:39 GMT
For cassandra all writes must be transmitted to all replicas.
CASSANDRA-1314 does not change how writes happen. Write operations
will still effect cache (possibly evicting things if cache is full).
Reads however will prefer a single node of it's possible replicas.
This should cause better cache utilization and less duplication for
those using READ.ONE with lower read repair settings.

It is also worth pointing out that the HBase cache is on entire hdfs
blocks, while Cassandra can cache on keys (key cache) or a key and all
it's columns (row cache). This has some deep implications based on how
random your reads are. Even with Cassandra's normal cache duplication
having more fined grained caches, of or rows rather then blocks, could
mean that they are more efficient anyway.

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