Groups and subgroups

Groups

A PGD cluster’s nodes are gathered in groups. A “top level” group always exists and is the group to which all data nodes belong to automatically. The “top level” group can also be the direct parent of sub-groups.

Sub-groups

A group can also contain zero or more subgroups. Subgroups can be used to represent data centers or locations allowing commit scopes to refer to nodes in a particular region as a whole. PGD Proxy can also make use of subgroups to delineate nodes available to be write leader.

The node_group_type value specifies the type when the subgroup is created. Some sub-group types change the behavior of the nodes within the group. For example, a Subscriber-only nodes sub-group will make all the nodes within the group into subscriber-only nodes.