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Date: Mon, 4 Nov 91 08:04:19 -0800
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From: seligman@starbase.MITRE.ORG (Len Seligman)
Subject: POSTGRES questions
To: postgres@postgres.berkeley.edu
Sender: pg_adm@postgres.berkeley.edu
Cc: kersch@gmuvax2.gmu.edu, len@starbase.mitre.org

I want to use POSTGRES to conduct some research on integrating
knowledge-based systems and databases.  After having read the 3.0 manual once
through, here are some questions:

1. I want to monitor a Postgres DB for certain conditions 
and notify my application
whenever those conditions are satisfied.  How do I handle the routing of
messages from my alerter rules?  I don't want to have to hand code all that
information on the right-hand side of every alerter rule.  Can I use portals?
(Note that my application is one which potentially could be running
continually.  Therefore, I can't make my application one large transaction.)
Does this require the (as-yet-unsupported) "attachas" command?

2. What meta-data are kept on rules?  (e.g., creator, purpose, etc.)  How
can this meta-data be queried?

3. Can rules be modified (e.g., to change the message produced by an
alerter rule, or to slightly modify the triggering condition)?  Can
they be activated and deactivated, as in HiPAC?  Or must they be deleted and 
recreated instead? 

4. Does use of the nested dot notation result in joining or in pointer
chasing?  (e.g., emp.dept.mgr.name)

5. Since multiple inheritance is supported (a la CLOS), how is the 
precedence order determined?  Also, is there any notion of before,
primary, and after methods as in CLOS?  Or is it the case that for any
given object and method, a single function will be selected and executed?
Thanks,

Len Seligman
The MITRE Corporation			(703) 883-5975
7525 Colshire Drive W418		FAX: (703) 883-6435
McLean, VA 22102			email: seligman@mitre.org