Currently, tablets need to be enabled per-keyspace by specifying the initial_tablets option, e.g.:

CREATE KEYSPACE test WITH replication = {'class': 'NetworkTopologyStrategy', 'replication_factor': 3, 'initial_tablets': 100};

We want keyspaces to be tablet-based by default when "tablets" experimental feature is enabled, and allow users to opt-out from it on per-keyspace basis via option: 'tablets': false.

This will make it easier to run all tests with tablets, by simply flipping the switch. Also, we want to make tablets enabled by default in the future, and not require users to opt-in in their DDL statements to use tablets.

Only NetworkTopologyStrategy currently supports tablets, so other strategies will remain vnode-based.

When 'initial_tablets' is not provided, it's chosen by the system based on current topology and RF so that all shards are covered:

initial_tablets = max(nr_shards_in(dc) / RF_in(dc) for dc in datacenters)