CODEWITHSUNDEEP
cassandra
Michaelzh
Michaelzh

Reputation: 490

In Cassandra how do I connect to only the nearby datacenter in a nation-wide cluster?

Say I have a Cassandra cluster with 3 datacenters, 1 in Beijiing, 1 in Changsha, and 1 in Shenzhen, now I want my client application running in Changsha only talk to C* nodes in Changsha, How do I do? Currently with the following code my client app is talking to all nodes in all datacenters in 3 cities, consequently the overall performance is drawn down by the latency between cities.

import com.datastax.driver.core.{Session, Cluster}

val cluster: Cluster = Cluster.builder().addContactPoints("10.10.11.71")
    .withRetryPolicy(DowngradingConsistencyRetryPolicy.INSTANCE)
    .withReconnectionPolicy(new ConstantReconnectionPolicy(100L))
    .withLoadBalancingPolicy(new RoundRobinPolicy)
    .build()
val session: Session = cluster.connect()

Upvotes: 0

Views: 302

Answers (1)

TheGeorgeous
TheGeorgeous

Reputation: 4061

The problem is in the Load balancing Policy. Round Robin has the behaviour you have described in your question. You should use the DC Aware Round Robin Policy. That will use the nearest data center but all the nodes. It is also possible to use a whitelist of nodes.

Upvotes: 3

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