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RE: Locally Managed Tablespaces - Questions.

From: Jacques Kilchoer <>
Date: Wed, 16 Apr 2003 17:28:37 -0800
Message-ID: <>

I will admit that I don't know at what point Steve Adam's recommendation would actually have an effect on performance. Here's another way to look at it:
Is there any situation where having a large number of extents is beneficial? For example is there any case that 50000 extents would be better than 5000? (Assuming each extent is large enough that any disk read will have to retrieve at least that amount of data.) As far as I know there is no benefit. So if you can predict the growth of your table, how does it hurt to use an extent size that will keep the number of extents in the thousands?

Which of course is your assumption with a ceiling of 4G on segment size, but I would think that segment sizes > 4G are not uncommon.

> -----Original Message-----
> From: Connor McDonald []
> Whilst I agree with Steve's assessment as it applies
> to squeezing the n'th degree of efficiency from
> Oracle, I'd be keen on hearing from anyone that
> suffered any detectable / noticeable performance
> degradation from having an excess of extent map blocks
> in their system.
> Don't get me wrong, I've no doubt that such a
> degradation must exist, but I'd be very surprised if
> there are many databases out there that are that well
> optimized so that this becomes a relevant issue.
> If that's the case, then I'm back to my argument that
> for almost all databases, you can quite happily get
> away with a 1m extent size for *every* segment in the
> database (assuming a 4G ceiling on segment size)

Please see the official ORACLE-L FAQ:
Author: Jacques Kilchoer

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Received on Wed Apr 16 2003 - 20:28:37 CDT

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