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Re: Tablespace/Datafile Layout for Datawarehouse

From: Greg Rahn <greg_at_structureddata.org>
Date: Wed, 13 Jun 2007 00:05:38 -0000
Message-ID: <1181693138.742529.286820@n15g2000prd.googlegroups.com>


On Jun 10, 1:29 pm, "Dereck L. Dietz" <diet..._at_ameritech.net> wrote:
> This is a datawarehouse so I'm thinking 16k block size. If there are tables
> that don't need the large I/O they can always be put in a separate
> tablespace with an 8k block size.
>
> As far as performance over recovery ... performance of the database here has
> taken a last place over the ease of management for the DBA at least in my
> opinion. If there is anything that can help the performance of the database
> but would cause the DBA more work it never happens.

An 8k block works fine for warehouses. I always use 8k and I've done benchmarks where a single table was over 20TB. I would stay away from mixed block sizes. There really is no need for it at all in a warehouse. The only real advantage of going to a larger block size is if you use compression. Since oracle uses block level compression, the more repeated values, the better the compression...and one can fit more data in a 16k block so it is possible to get a bit of extra compression.

Either way, chose one size and stick with it.

Remember, the IO size is governed more by the multi block read count, rather than the block size.

--
Regards,

Greg Rahn
http://structureddata.org
Received on Tue Jun 12 2007 - 19:05:38 CDT

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