Table Replication

Data in one table can be replicated to another table that is in the same cluster or in a separate cluster. This type of replication is in addition to the automatic replication that occurs with table regions within a volume.

You can replicate changes (puts and deletes), entire tables, specific column families, and specific columns.

Note: MapR binary tables can only be replicated to binary tables; MapR JSON tables can only be replicated to JSON tables.
  • Tables that data is replicated from are called source tables, while tables that data is replicated to are called replicas.
  • Clusters that data is replicated from are called source clusters. Clusters that data is replicated to are called destination clusters. A single cluster can be both a source cluster and a destination cluster, depending on the replication configuration in which the cluster participates.
  • Replication takes place between source and destination clusters. However, source clusters do not send data to nodes in the destination cluster directly. The replication stream (the data being pushed to the replicas) is consumed by one or more MapR gateways in the destination cluster. The gateways receive the updates from the source cluster, batch them, and apply them to the replica tables. Multiple gateways serve the purpose of both load balancing and failover.

For more information about gateways, see “Administering MapR Gateways.

Note: The maximum number of replicas that a source table can replicate to is 64. The maximum number of source tables that a replica can accept updates from is 64.