To define a new user, run the createuser utility program.
To assign a user or set of users to a new group, one must define the group itself, and assign users to that group. In Postgres these steps are not currently supported with a create group command. Instead, the groups are defined by inserting appropriate values into the pg_group system table, and then using the grant command to assign privileges to the group.
Currently, there is no easy interface to set up user groups. You have to explicitly insert/update the pg_group table. For example: jolly=> insert into pg_group (groname, grosysid, grolist) jolly=> values ('posthackers', '1234', '{5443, 8261}'); INSERT 548224 jolly=> grant insert on foo to group posthackers; CHANGE jolly=> The fields in pg_group are: * groname: the group name. This a name and should be purely alphanumeric. Do not include underscores or other punctuation. * grosysid: the group id. This is an int4. This should be unique for each group. * grolist: the list of pg_user id's that belong in the group. This is an int4[].