From: | Michael Fuhr <mike(at)fuhr(dot)org> |
---|---|
To: | Roy Souther <roy(at)SiliconTao(dot)com> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: How can I make SELECT return tuple numbers? |
Date: | 2005-07-06 04:11:22 |
Message-ID: | 20050706041122.GA1529@winnie.fuhr.org |
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Lists: | pgsql-general |
On Tue, Jul 05, 2005 at 09:55:48PM -0600, Michael Fuhr wrote:
>
> You could reset a sequence's start value before each insert. You
> might even be able to it automagically with a statement-level before
> trigger that resets the sequence value and a DEFAULT expression or
> row-level trigger that uses nextval() to obtain the next sequence
> value. That appears to work in simple tests, although I admittedly
> haven't thought it through very far to see if there would be any
> problems.
One problem would involve concurrent inserts obtaining values from
the same sequence; I think using a temporary (i.e., session-local)
sequence should mitigate that problem. You could create the sequence
in a statement-level before trigger and drop it in a statement-level
after trigger to make its use somewhat invisible. But again, I've
only done this in simple tests, so it deserves more thought.
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/
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