It is viable provided that you note that keys and indexes must be declared on each child table.

In fact this is pretty close to an ideal use for table inheritance. Just make sure you are familiar with the gotchas, and that you pay close attention to foreign key creation in the user schemas.

One caveat is that you can't cascade CREATE statements into all the schemas. This would have to be scripted. You could however create plpgsql functions to do this. Just note that such statements usually are not parameterized so you need to use quote_ident() and quote_literal as appropriate.

It is viable provided that you note that keys and indexes must be declared on each child table.

In fact this is pretty close to an ideal use for table inheritance. Just make sure you are familiar with the gotchas, and that you pay close attention to foreign key creation in the user schemas.

One caveat is that you can't cascade CREATE statements into all the schemas. This would have to be scripted. You could however create plpgsql functions to do this. Just note that such statements usually are not parameterized so you need to use quote_ident() and quote_literal as appropriate.

As per request here's an example. In the master schema. Note the key and unique constraints here are for documentation purposes only.

CREATE SCHEMA master;
SET SEARCH_PATH="master;

CREATE TABLE users (
   id bigserial not null unique,
   login text primary key,
   check (false) NO INHERIT -- 9.2 ONLY, prevents any rows in this table
);

CREATE TABLE roles (
   id bigserial not null unique,
   role_name text primary key,
   check (false) NO INHERIT -- 9.2 ONLY, prevents any rows in this table
);

CREATE TABLE user_roles (
   user_id bigint references users(id),
   role_id bigint references roles(id),
   primary key (user_id, role_id)
   check (false) NO INHERIT -- 9.2 ONLY, prevents any rows in this table
);

RESET SEARCH_PATH;

Naturally if not on PostgreSQL 9.2 drop the check constraints since they would be inherited in prior versions and then no tables could have rows.

Then in a child schema:

CREATE SCHEMA customer123;
SET SEARCH_PATH 'customer123';

CREATE TABLE users(unique (id), primary key(login)) INHERITS (master.users);
CREATE TABLE roles(unique (id), prikary key(role_name)) INHERITS (master.roles);
CREATE TABLE user_roles(
     foreign key users_id REFERENCES customer123.users(id),
     foreign key role_id REFERENCES customer123.roles(id),
     primary key (users_id, role_id)
);
RESET SEARCH_PATH; 

Note in this case you must carefully control access to the master schema because:

SELECT tableoid, login from master.users;

gives you every user account of every tenant plus enough info to determine which tenant it is.