org.apache.cassandra.db.view

Class ViewUtils

java.lang.Object

org.apache.cassandra.db.view.ViewUtils

public final class ViewUtils
extends java.lang.Object

Method Summary

Modifier and Type	Method and Description
static java.util.Optional<Replica>	getViewNaturalEndpoint(AbstractReplicationStrategy replicationStrategy, Token baseToken, Token viewToken) Calculate the natural endpoint for the view.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getViewNaturalEndpoint

public static java.util.Optional<Replica> getViewNaturalEndpoint(AbstractReplicationStrategy replicationStrategy,
                                                                 Token baseToken,
                                                                 Token viewToken)

Calculate the natural endpoint for the view. The view natural endpoint is the endpoint which has the same cardinality as this node in the replication factor. The cardinality is the number at which this node would store a piece of data, given the change in replication factor. If the keyspace's replication strategy is a NetworkTopologyStrategy, we filter the ring to contain only nodes in the local datacenter when calculating cardinality. For example, if we have the following ring: A, T1 -> B, T2 -> C, T3 -> A For the token T1, at RF=1, A would be included, so A's cardinality for T1 is 1. For the token T1, at RF=2, B would be included, so B's cardinality for token T1 is 2. For token T3, at RF = 2, A would be included, so A's cardinality for T3 is 2. For a view whose base token is T1 and whose view token is T3, the pairings between the nodes would be: A writes to C (A's cardinality is 1 for T1, and C's cardinality is 1 for T3) B writes to A (B's cardinality is 2 for T1, and A's cardinality is 2 for T3) C writes to B (C's cardinality is 3 for T1, and B's cardinality is 3 for T3)

Returns:

Optional.empty() if this method is called using a base token which does not belong to this replica