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RE: extent allocation

From: Ron Rogers <RROGERS_at_galottery.org>
Date: Wed, 23 Jun 2004 08:22:03 -0400
Message-Id: <s0d93dc2.055@galottery.org>


I would have to say that extent size does matter but depends on what you are placing in the tablespace. Why would you want to have 100 M extents when the tablespace will contain table that are small such as 4 K. When the tablespace has to increase in size it will consume a lot of space just for a small table. On the other hand if the tablespace extent size is small and the table extents are large and numerous there most likely will be a lot of disk thrashing to get the data as the extents could be all over the disk and not contiguous.
 I think that it is better to plan the database layout and keep like sized object in a like sized tablespace as much as possible. I prefer to use the uniform extent size method as it allows me to plan the disk layout and future growth capabilities for the disks. With autoallocate the growth pattern looks logarithmic and increases in size dramatically as the number of extend increases. Ron

>>> Jacques.Kilchoer_at_quest.com 06/22/2004 9:20:18 PM >>>
I don't think anyone is going to argue AGAINST uniform extent allocation. However, some people have argued AGAINST autoallocate. If you made all tablespace uniform no one would be able to say you made
the wrong choice.

The next question is, what size should you make your uniform extents? A: Since number of extents is irrelevant (this also seems to be the consensus on this list), then I would say that the extent size doesn't really matter either.

-----Original Message-----
Harvinder Singh

It will be great if you can point me to articles/white papers explaining
advantages/disadvantages of using autoallocate/uniform extent allocation
for LMT



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Received on Wed Jun 23 2004 - 07:19:37 CDT

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