From where cassandra fetch data for select?

Question

I understand the concept of SSTable in Cassandra. I have also tested the different version of files create with insert after nodetool flush.

I have also setup a snapshot backup and incremental back and tested it's working fine.

For testing purpose i deleted all the sstable files from all the nodes. Strangely , am still able to select the data. Can someone please explain me from where cassandra is fetching the data ?

Regards Sid

Answer 1

The record you queried was available in the ROW cache aka memtables(memory).

So once you restart your node strangely you will again get back the result because the commit logs got replayed eventually building those SSTables for you.

Clear all the SSTables and commit logs and restart your node .And then you can observe that you get no records for your query .