Node Group

[number_of_node_groups] = number_of_data_nodes / NoOfReplicas

Partition

When using ndbd, the maximum number of partitions that may be defined explicitly for any NDB table is 8 * [number of node groups]. (The number of node groups in a MySQL Cluster is determined as discussed previously in this section.)

When using ndbmtd, this maximum is also affected by the number of local query handler threads, which is determined by the value of the MaxNoOfExecutionThreads configuration parameter. In such cases, the maxmimum number of partitions that may be defined explicitly for an NDB table is equal to 4 * MaxNoOfExecutionThreads * [number of node groups].

Replica

The number of replicas is equal to the number of nodes per node group

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