Question: You said that Cassandra doesn't provide easy searching, but can't the same be said about PostgresSQL as well? As in, you can't store petabytes of data on one machine, you've got to shard your PostresSQL onto multiple machines, just as a Cassandra does. And let's assume that you're not searching on primary key, won't PostgresSQL need to scan through each sharded DB just a Cassandra would've had to?
