ALTER GROUP — change role name or membership
ALTER GROUPgroupnameADD USERusername[, ... ] ALTER GROUPgroupnameDROP USERusername[, ... ] ALTER GROUPgroupnameRENAME TOnewname
ALTER GROUP changes the attributes of a user group.
This is an obsolete command, though still accepted for backwards
compatibility, because groups (and users too) have been superseded by the
more general concept of roles.
The first two variants add users to a group or remove them from a group. (Any role can play the part of either a “user” or a “group” for this purpose.) These variants are effectively equivalent to granting or revoking membership in the role named as the “group”; so the preferred way to do this is to use GRANT or REVOKE.
The third variant changes the name of the group. This is exactly equivalent to renaming the role with ALTER ROLE.
groupnameThe name of the group (role) to modify.
username Users (roles) that are to be added to or removed from the group.
The users must already exist; ALTER GROUP does not
create or drop users.
newnameThe new name of the group.