That's the first idea I've seen that looks like it might actually work... (Not that the other ideas were bad, but I just couldn't see how I could fit the solutions into my current app)

So what would my user setup look like?  Would it look something like this:

createuser joe
grant select on schema company_a to joe
(whatever other permissions)
alter user joe set search_path='common','company_a';

createuser bob
grant select on schema company_b to bob
(whatever other permissions)
alter user bob set search_path='common','company_b';

How portable is all of this? Could a comparable structure be implemented in MS SQL or Oracle?


Niklas Johansson wrote:

How about this:

* Have one master schema that holds all physical tables. This schema is accessible only by the superuser.

* Create a schema which contains views that mirror the master schema. This is the schema that the customers connect to, each using a different db role, and since it's a mirror of the master schema, it means no change in app structure (except dropping rights management, see below).

* Let these views pull their data from the respective master schema table (i.e. SELECT * FROM ...) with the addition of a WHERE-clause on client_id, that uses a function: ...WHERE client_id IN (get_client_ids ()).

* The 'get_client_ids()'-function should query a table in the master schema that keeps the client_id's that are assigned to each db role (e.g. SELECT client_id FROM foo WHERE role=CURRENT_USER), and return those client_id's. For a regular customer, it would return one client_id, for a supervisor kind of user, it would return two or more, perhaps even all, client_id's.

* Have UPDATE and INSERT rules on the views that store the data in the actual master schema tables. (The rules would of course have to add client_id, this time through a function that can only return one client_id.)

To conclude: one master schema, one mirrored customer schema that adapts to the db role, one additional table in the master schema to handle the rights.


Sincerely,

Niklas Johansson
Phone: +46-322-108 18
Mobile: +46-708-55 86 90




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