Re: BUG #9485: RFE - cycling sequence rollover to do modulo

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Paul(dot)Murray(at)environment(dot)gov(dot)au
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #9485: RFE - cycling sequence rollover to do modulo
Date: 2014-03-09 23:47:15
Message-ID: 20140309234715.GH4759@eldon.alvh.no-ip.org
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Paul(dot)Murray(at)environment(dot)gov(dot)au wrote:

> When a sequence with a cycle does a rollover, it sets itself to its minimum
> value.
>
> I would like an option to create a sequence that resets to the minimum value
> plus the amount by which the next number exceeded the maximum. Perhaps like
> this:
>
> create sequence foo increment 616 min value 0 maxvalue 999 cycle modulo;

Would this be useful?

http://www.postgresql.org/message-id/CA+U5nMKh+pmbaGUd_x9ev-F5k+whT8HM7wXfkX9ouF=cPkAQEg@mail.gmail.com

You'd have to create a new "sequence access method" that provided the
behavior you want.

I think it'd be interesting to have an implementation of the behavior
you want on top of the proposed patch.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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