DB has not crashed! However, it has been stopped for exports and backups a
few times.. would stop/starting the instance be enough to make it discard
the cached values and start over with a new set?
TIA.
> In general you should not be skipping blocks of
> values, but it can happen under some circumstances
> (such as a database crash, or export/import cycle).
> The skip would also be a quantity up to the cache
> size, rather than exactly the cache size.
>
> The cache operates by updating sys.seq$ table,
> and keeping an in-memory track of that value until
> calls to nextval reach it - at this point seq$ is updated
> again and the process repeats. This is why a crash
> can cause a jump.
>
> If you go to NOCACHE (or ORDERED, I think) then
> seq$ is updated every time nextval is used - the
> overhead can be quite significant in very busy systems
> as both rollback and redo are generated and the
> recursive transaction has to commit - if you are running
> to dozens of calls per minute, then the performance
> impact can be quite noticeable.
>
> --
>
> Jonathan Lewis
> Yet another Oracle-related web site: www.jlcomp.demon.co.uk
>
> D. Oakley wrote in message ...
> >(Running Oracle 7.3 on Unix)
> >
> >Hi,
> >
> >I was having a problem with a sequence generator that i was using in that
> it
> >seemed to be skipping numbers in blocks of 20. I presumed this was being
> >caused by the default cache setting of 20. Firstly, is this a safe
> >presumtion?
> >
> >Secondly, what effect will there be on performance of the sequence
> generator
> >if I set the caching to NOCACHE?
>
>
>
Received on Thu Apr 22 1999 - 06:56:17 CDT
