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Re: Update a table with no logging?

From: Bart <a_at_a>
Date: Tue, 15 May 2001 19:35:42 +0100
Message-ID: <989948404.14397.0.nnrp-13.9e985e86@news.demon.co.uk>

"Howard J. Rogers" <howardjr_at_www.com>
>
> The process makes the insert really fast -because we know we are going to
 be
> writing into blocks above the high watermark, we can be fairly cavalier in
> the way we do it... we're guaranteed there's no existing data there that
 has
> to be slotted in (by the very definition of what a HWM represents).
>
> That makes the load extremely fast.
>
> But you never get nothing for free with Oracle. The price to pay for
> bluntly slamming complete blocks down onto disk is that there is NO
 clever,
> subtle update of the relevant indexes, as there would be with a more
 subtle,
> clever normal insert. So, yes... your indexes are toast, and you have to
> rebuild them. Allegedly, you still win in the end: the load goes so much
> faster that the extra time spent rebuilding indexes is usually not enough
 to
> counteract the gain (that's the theory, anyway).
>

Correct me if I'm wrong, but Oracle "rebuilds" the indexes for you, rather than invalidating them and forcing you to rebuild them yourself - if so, surely it does an inteligent bulk update rather than a full index rebuild.

I realised (or thought I did) that Oracle updated the index after completing the INSERT, but I though it was performing some form of inteligent bulk update.

If I do a relatively small DIRECT PATH insert on a large table, it performs a magnatude faster than a full rebuild of my indexes would.

I think I've missed something along the way. Received on Tue May 15 2001 - 13:35:42 CDT

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