Re: Full export and sequence behaviour in 8i

2009/3/16 Dan Norris <dannorris@xxxxxxxxxxxxx>:
> Never is a word I don't see too often. I think a "nocache order" sequence is
> better and more reliable than any other method I've seen. What approach
> would you use instead to have a no-gap list of numbers guaranteed?

Word "guaranteed" isn't appropriate here. Maybe word "less
probability" to get gaps could be used to explain this situation. As
Neil already explained there are certain scenarios which can grab
sequence value and as soon as it is grabbed you'll never get it back.
Of course probablity for DB crash and (depending on your app) to
rollback a transaction is less than aging sequence out of cache or DB
restart, which certainly looses cached sequence values. 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

Gints Plivna
http://www.gplivna.eu
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http://www.freelists.org/webpage/oracle-l

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