Re: Switching roles as an replacement of connection pooling tools

On 31/05/2016 10:45, CN wrote:

I have a feeling that slight enhancement to commands "SET ROLE" or "SET
SESSION AUTHORIZATION" can obsolete and outperform external connection
pooling tools in some use cases.

Assume we are in the following situation:

- There are a million schemas each owned by a distinct role.
- Every role is not allowed to access any other schema except its own.

If command "SET SESSION AUTHORIZATION" is enhanced to accept two
additional arguments

PASSWORD <password>

, then a client simply establishes only one connection to server and do
jobs for a million roles.

Say I want to gain full access to "schema2", I simply issue these two
commands

SET SESSION AUTHORIZATION user2 PASSWORD p2;
SET SEARCH_PATH TO schema2,pg_category;

, where "p2" is the password associated with role "user2".

If the current role is superuser "postgres" and it wants to downgrade
itself to role "user3", then it simply sends these commands:

SET SESSION AUTHORIZATION user3;
SET SEARCH_PATH TO schema3,pg_category;

Does my points make sense?
Is it eligible for feature request?

I believe your thoughts are on the same line with an idea some people had about using connection pools on Java EE environments, in a manner that does not use a generic "catch all" user, but uses the individual users sharing the security context from the app server.
This way one could have the benefits of the connection pool, and the benefits of fine-grained and rich PostgreSQL security framework, the ability to log user's activity, debug the system easier, see real users on pg_stat_activity, on ps(1), on top(1) etc etc.
The way we do it currently is by having personalized connection pools for pgsql in jboss. It does the job from every aspect, except one : it sucks as far as performance is concerned. Every user is tied to his/her number of connections. It creates a sandbox around each user, so that a "malicious" greedy user (with the help of a poorly designed app of course) can only bring down his own pool, while others run unaffected, but still performance suffers. The idea would be to use a common pool of connections and assign users on demand as they are taken from the common pool, and later also return them to the common pool, once closed.
Whenever I talked to PG ppl about it, they told me that redesigning the SET ROLE functionality so that it correctly applies all the security checks and also so that it results in reflecting the effective user in all references in logs, sys views, OS (ps, top, etc) etc.. was hard to do, and the convo stopped right there.

With all the new and modern cloud-inspired paradigms out there, our traditional architecture might not of much interest any more, still I would love to make the above happen some time.

Best Regards,
CN

--
Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt

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