If your data fits into memory you probably do not need NoSQL.
You may also notice the company that produced the benchmark is a cloudera partner so they "forgot" to show how much faster couchdb is then hbase in this scenario, but were more then happy to show you how much "faster" it is then mongo and cassandra .
On Wed, Dec 12, 2012 at 12:34 PM, Radim Kolar <email@example.com>
if dataset fits into memory and data used in test almost fits into memory then cassandra is slow compared to other leading nosql databases, it can go up to 10:1 ratio. Check infinispan benchmarks. Common use pattern is to use memcached on top of cassandra.
cassandra is good if you have way more data then your RAM size. It beats SQL database 10:1 ratio at cost low flexibility for queries.