When using a MySQL database, it was possible to run queries against system tables to find the elements with the highest impact on the database (in terms of size and number of rows). Is this also possible when using Cassandra?
I don't know about a certain query to easily show you such data, there could be such a query, but I'm no CQL wizard.. (maybe ask the Cassandra Champion?)
We tend to use the Cassandra Cluster Validator to see which element holds the most data and has the most datapoints (Elements page in the element).
If you decide to create such an element, be sure to check the driver help, as quite some things could go wrong.
When retrieving this data, know that it can take a while before you get results (might take hour(s)).