Re: Running time of index rebuild

thank you everybody who replied and for stopping me from accidentally breaking things.

I will have to put a lot more thought in this...

There is plenty of CPU but not memory. Sort took place on disk during the test run, so probably no major performance hit due to access time. Lack of temp space will be a (workaroundable) problem. Perhaps archivelog space too.
During the maintenance window the major "insert" processes will be stopped, but not all customer access.

At the moment both drop/create and rebuild online sound better than the original idea, but before deciding anything I'll check out the OTN link, its references and the details provided by Jonathan. If anything interesting comes from experimenting / implementing the rebuild I'll get back to the group.

And last: Sorry for the unreadable message. (Hopefully) improved version below.

Best regards
Ingrid Voigt

On 05.06.2013 16:56, Ingrid Voigt wrote:

> Hi,
>
> does anybody know how the running time for index create or rebuilds
> in Oracle changes withnumber of lines / table size? I would expect
> O(n log n)?
>
> We need a guesstimate for the time for a complete rebuild where the
> test environment is considerably smaller:
>
> TEST: 19 mio rows / 16 GB / 15 minutes
> PROD: 894 mio rows / 725 GB / ???
>
> Refilling test with complete production data is not an option.
>
> I know that index rebuilds are not usually necessary. In this case we
> need to gain enough space in the database to last until the new SAN
> is usable, and 50 GB (as predicted by the segment advisor) would
> be very helpful.
>
>
> My suggestion for the maintenance window on prod would be
> 16 hours, do you have a better idea?
>
>
> Best regards
> Ingrid Voigt

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