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Re: Locally Managed Tablespaces - Questions.

From: Chip <>
Date: Fri, 11 Apr 2003 22:24:22 -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.

Depends - if the size (including annual growth) of an object is known, then uniform size makes a lot of sense. Remember to add 64 K (bitmap) to a multiple of the uniform size when creating a data file.

If the expected object size and growth is unknown (e.g. vendor application), then autoallocate is wonderful. The objects can be created in autoallocate tablespaces. When an object grows too big (either an autoallocate tablespace
is getting full or an object grows over 8 GB in size), then move a large object to an appropriate uniform size tablespace. Note: the space freed up in the autoallocate tablespace will always be a multiple of 64 K, which can readily be reused as smaller objects grow or new objects are added.

Have Fun :)

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Author: Chip

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Received on Sat Apr 12 2003 - 01:24:22 CDT

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