The number of replicas assigned to a topic created with CREATE TABLE.

Data Type

int

Default Value

3

Remarks

When executing a CREATE TABLE statement, the driver creates a new empty topic. By default, the driver creates this topic with a replication factor of 3.

You can create topics with a different number of replicas by changing this setting. There are two main cases where this is useful:

• When your cluster has fewer than 3 nodes. This setting should never be higher than the number of nodes in your cluster. For example, creating topics with a replication factor of 3 on a cluster with 2 nodes will fail.
• When your cluster has more than 3 nodes and you want more safety in case of failover. Apache Kafka uses replicas to prevent data loss when a node fails, and if all the replicas fail then the topic is unavailable.