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RE: Locally Managed Tablespaces - Questions.

From: Niall Litchfield <>
Date: Fri, 11 Apr 2003 13:08:38 -0800
Message-ID: <>

> Hi Listers,
> I am in the process of setting up a new Oracle database on
> I want to use locally managed tablespaces, but im
> not sure about the extent and segment management options.
> Should I use uniform extents? If so how do i determine a good
> size for these, or is the Oracle Default good enough.

I would say definitely use uniform extent sizes. You don't want to reorg later after all. As to what sizes to use I would suggest that the sizes oracle uses in its own auto-allocate policy (64k,1m,64m,256m) seem reasonable, provided only that these are multiples of a) the multiblock read count* block size - because that is what oracle will request at a time and b) what the io subsystems can actually provide in one read.

> Also
> what about sement space management, what benefits can this
> provide me, any potential pitfalls i should watch out for?

ASSM is designed to avoid problems of freelist contention. If you don't expect to see it why use ASSM? I'd be nervous because a) the docs refer to t as a feature designed with RAC in mind and b) its in version 1.1 (or thereabouts). This doesn't constitute proof that its bad (the dev db I created with ASSM has had no issues at all just a reason to be a bit suspicious.

> Also should i make my system tablespace locally managed also?

I'd say yes. LMTs are good (and likely mandatory from 10)

> Does this mean i then cant create dictionary managed tablespaces?

Yes it means exactly that, though you can under certain circumstances plug them in as transportable tablespaces.



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Author: Niall Litchfield

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Received on Fri Apr 11 2003 - 16:08:38 CDT

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