Re: Full export and sequence behaviour in 8i

From: Dan Norris <dannorris_at_dannorris.com>
Date: Mon, 16 Mar 2009 09:39:47 -0500
Message-ID: <49BE64B3.5010408_at_dannorris.com>

I completely agree regarding performance. As you indicate, if you really want gapless, you apparently are willing to sacrifice performance.

I like the doc, but I do think you've overstated the sequences bit (I don't like "never"). I agree that oracle only guarantees unique numbers from sequences, but in a completely controlled (perhaps contrived) and unrealistic environment, sequences could provide gapless consecutive numbers. You'd just have to wrap the scenario with a bunch of unrealistic conditions like:
--the environment never crashes
--transactions are never rolled back (intentionally or unintentionally, like from crashes, killed sessions, etc) --errors in the application never occur
--there are no bugs in Oracle that may impact sequences or their use

I think with these conditions spelled out, it would be easier for people to see that sequences can provide gapless, consecutive sequential numbers, but it just isn't safe to do so (therefore, it isn't "never", but "really, really unlikely"). See...told you my devil's advocate was turned back on :) !

Dan

Gints Plivna wrote:
>
> Also nocached
> sequence might be sort of bottleneck especially in RAC scenarios. Of
> course it depends on sequence usage rate. And this requirement to get
> guaranteed numbers without gaps is asking for bottlenecks per se as
> I've tried to explain here
> http://www.gplivna.eu/papers/gapless_sequences.htm
>

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Received on Mon Mar 16 2009 - 09:39:47 CDT