The catalog pg_group defines groups and stores what users belong to what groups. Groups are created with the CREATE GROUP command. Consult Chapter 17 for information about user privilege management.
Because user and group identities are cluster-wide, pg_group is shared across all databases of a cluster: there is only one copy of pg_group per cluster, not one per database.
Table 41-15. pg_group Columns
|groname||name||Name of the group|
|grosysid||int4||An arbitrary number to identify this group|
|grolist||int4||pg_shadow.usesysid||An array containing the IDs of the users in this group|