Can I prevent a keyspace from syncing over to another datacenter by NOT including the other datacenter in my keyspace replication definition? Apparently, this is not the case.

In my own test, I have set up two Kubernetes clusters in GCP, each serves as a Cassandra datacenter. Each k8s clusters have 3 nodes.

I set up datacenter DC-WEST first, and create a keyspace demo using this: CREATE KEYSPACE demo WITH replication = {‘class’: ‘NetworkTopologyStrategy’, ‘DC-WEST’ : 3};

Then I set up datacenter DC-EAST, without adding any use keyspaces.

To join the two data centers, I modify the CASSANDRA_SEEDS environment variable in the Cassandra StatefulSet YAML to include seeds nodes from both datacenters (I use host networking).

But after that, I notice the keyspace demo is synced over to DC-EAST, even though the keyspace only has DC-WEST in the replication.

cqlsh> select data_center from system.local
... ;

data_center
-------------
DC-EAST     <-- Note: this is from the DC-EAST datacenter

(1 rows)
cqlsh> desc keyspace demo

CREATE KEYSPACE demo WITH replication = {'class': 'NetworkTopologyStrategy', 'DC-WEST': '3'}  AND durable_writes = true;

So we see in DC-EAST the demo keyspace which should be replicated only on DC-WEST! What am I doing wrong?