Message-ID: <454AB42F.9080406@nwlink.com>
Date: Thu, 02 Nov 2006 19:14:55 -0800
From: Glen Parker <glenebob@nwlink.com>
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To: pgsql-general@postgresql.org
Subject: Re: Is there anyway to...
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Wes Sheldahl wrote:
> if you did have a cron 
> job run to check, you would probably just have it set a boolean field on 
> expired records or something of that sort, and run it a little after 
> midnight, at the start of each day, assuming durations were always being 
> measured in days.

Exactly.  You flag when you discover an expired condition, and you flag 
again when the condition is acted upon.  Easy.  The instructor doesn't 
need to be bothered any more than you choose.  You could even set a 
timestamp indicating the last time the instructor was harrassed about 
it, so you can re-harrass on a daily or weekly basis :-)

Now, my example that had the expire query run when the instructor logs 
on was just to illustrate that if you do this right, it doesn't matter 
when the code runs.  Personally, I'd have a cron job do it at midnight, 
but whenever it runs, even if it's multiple times a day, the outcome 
should still be correct. That's where your status flags come in.  Once a 
record has been expired, there's no reason for your expire code to ever 
look at that record again, right?

-Glen