I've a Cassandra table (Cassandra version is 2.0) with terabytes of data, here is what the schema looks like

```
"my_table" (
  key ascii,
  timestamp bigint,
  value blob,
  PRIMARY KEY ((key), timestamp)
)

```

I'd like to delete some data, but before want to estimate how much disk space it will reclaim. 

Unfortunately stats from JMX metrics are only available for last two weeks, so thats not very useful.

Is there any way to check how much space is used by certain set of data (for example where timestamp < 1000)?

I was wondering also if there is a way to check query result set size, so that I can do something like `select * from my_table where timestamp < 1000` and see how many bytes the result occupies.