Message-ID: <454A3EB6.8080806@linuxlouis.net>
Date: Thu, 02 Nov 2006 13:53:42 -0500
From: louis gonzales <gonzales@linuxlouis.net>
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To: brian <brian@zijn-digital.com>
CC: pgsql-general@postgresql.org
Subject: Re: Is there anyway to...
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Hey Brian,
Yeah I had considered this, using cron, I just feel like that is too dirty.

Actually I didn't see Andreas' post, can someone forward that?

I'm running this application on Solaris 9.  Ultimately what I want to 
know is, is there something that is internal to postgresql that can be 
used that doesn't need external action, to make it do some task?

Some built in function that can be set to do some simple task on a daily 
- or other time - interval, where all of the defined users may not have 
any activity with the database for day's or week's at a time, but this 
builtin function still operates?

Am I making any sense with how I'm asking this?  I could of course have 
cron do a scheduled task of checking/incrementing/decrementing and 
define triggers to occur when one of the cron delivered actions sets the 
appropriate trigger off, but are there other methods that are standard 
in the industry or are we stuck with this type of external influence?

Thanks all!

brian wrote:

> louis gonzales wrote:
>
>> Hello all,
>> Is there an existing mechanism is postgresql that can automatically 
>> increment/decrement on a daily basis w/out user interaction?  The use 
>> case I'm considering is where a student is in some type of contract 
>> with an instructor of some sort, and that contract puts a time limit 
>> on the student requiring her to pay a fee by a certain day.  IF that 
>> day comes to pass - or a certain number of days elapse - and that 
>> payment requirement hasn't been met, I want to trigger a function.
>>
>> The one requirement I want to impose is, that no end user of the DB 
>> application, needs to do anything to set the trigger, other than the 
>> initialization of making the student of this type.
>>
>> An example would be:
>> Day1 - Application user(typically the instructor) creates a profile 
>> for a new student - John Doe, which sets a 30 day time limit for John 
>> Doe to pay $100.00
>> Day2 -> Day31 - John Doe didn't make the payment
>> Day 31 - Trigger of event occurs when the instructor logs in.
>>
>> Basically on Day 1 when John Doe's profile was created, I want a 
>> decrement counter to occur daily on his profile(some attribute/timer) 
>> and nothing should happen until day 31 when he doesn't pay.
>>
>
> Further to Andreas' suggestion to use CRON, you don't require a 
> decrement of anything. When the profile is created, your date_created 
> (or whatever) column will be set. Then your script (called by CRON) 
> only needs to test for rows that a) have not paid, and b) are outside 
> the bounds set in the script (eg. MAX_GRACE_PERIOD = 30).
>
> brian
>
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