PostgreSQL Security/Roles/Grants

Hi,

I come from an Oracle background and wonder if anyone could provide some background information on how best to implement an application security scheme in PostgreSQL using roles / grants.

I'd just like to outline first how I'd approach security in Oracle:

There is a notion of both:

1. Default Roles -> a role which is activated at login time. Oracle imposes a limit on the number of default roles which any given user can have.

2. Non-default role -> a role which has to be explicitly activated during the lifecycle of an application in order to gain access to database resources. There are no limits on the number of non-default roles. This type of role helps us to only provide a user with the minimal set of privileges that they require at any given time, and minimise their access to database resources.

I have looked through the PostgreSQL documentation, and cannot find anything analogous to the 'non-default role' which I have outlined above - although obviously it does support roles.

I just want to confirm that all roles in postgreSQL are activated at login time?

Secondly, is there a limit on the number of roles which can be assigned to a user (or more accurately a 'login role') in postgreSQL?

Many thanks,

Andrew.

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