Changing keyspace replication strategy
A keyspace is created with a replication strategy.
For development, the SimpleStrategy class is acceptable.
For production, you must use NetworkTopologyStrategy.
To change the strategy, alter the distribution of nodes within multiple datacenters by adding a datacenter, and then add data to the new nodes in the new datacenter and remove nodes from the old datacenter.
Procedure
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If necessary, change the snitch to a network-aware setting.
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Alter the keyspace properties using
ALTER KEYSPACE:-
Example 1: Switch the keyspace cycling from
SimpleStrategytoNetworkTopologyStrategyfor a single datacenter:cqlsh> ALTER KEYSPACE cycling WITH REPLICATION = {'class' : 'NetworkTopologyStrategy', 'DC1' : 3}; -
Example 2: Switch the keyspace cycling from
SimpleStrategytoNetworkTopologyStrategyfor two datacenters:cqlsh> ALTER KEYSPACE cycling WITH REPLICATION = {'class' : 'NetworkTopologyStrategy', 'DC1' : 3, 'DC2' : 2 };Simply altering the keyspace may lead to faulty data replication.
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Run
nodetool repairusing the-fulloption on each node affected by the change.nodetool repair -full keyspaceTarball and Installer No-Services path:
<installation_location>/resources/cassandra/bin
It is possible to restrict the replication of a keyspace to selected datacenters or a single datacenter. To do this, use the
NetworkTopologyStrategyand set the replication factors of the excluded datacenters to0(zero):cqlsh> ALTER KEYSPACE cycling WITH REPLICATION = {'class' : 'NetworkTopologyStrategy', 'DC1' : 0, 'DC2' : 3, 'DC3' : 0 };
