From: | Scott Marlowe <smarlowe(at)g2switchworks(dot)com> |
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To: | Andrew Sullivan <ajs(at)crankycanuck(dot)ca> |
Cc: | "'pgsql-sql(at)postgresql(dot)org'" <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Column with recycled sequence value |
Date: | 2005-01-13 21:57:04 |
Message-ID: | 1105653424.24795.111.camel@state.g2switchworks.com |
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Thread: | |
Lists: | pgsql-sql |
On Thu, 2005-01-13 at 15:43, Andrew Sullivan wrote:
> On Thu, Jan 13, 2005 at 03:31:54PM -0600, Scott Marlowe wrote:
> > Any method that tries to reuse sequence numbers is a bad idea (TM) and
>
> Why? I can think of a dozen cases where it can be useful. It just
> depends on the application.
The usual, if it's a PK of a FK relationship it's possible to have an
orphaned set at some point pointing back to it, race conditions on
trying to find a reusable sequence number, and the poor performance
needed to lock it to reuse it.
What cases are you thinking of? I've seen some very limited ones, like
using a short range for managing a queue, but that avoids a lot of the
performance issues since it's a small set you're trundling through to
find the next one available. But they're not that common, and most of
the time someone is thinking of doing so it's because a boss who doesn't
get it wants a pretty list with no holes in the sequence or something
equally silly.
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