[askdba] Re: Need help with Interview Questions
- From: Ganesh Raja <ganesh.raja@xxxxxxxxx>
- To: askdba@xxxxxxxxxxxxx
- Date: Mon, 8 Nov 2004 16:47:19 +0000
Okay Read this Intresting Post ..
http://www.jlcomp.demon.co.uk/one_extent.html
Guys . Pls Dont Start to Compress to One Extent after u have read this
Post .. It does not make sense .. Think abt other stuff first ... as
Jonathan Lewis Says there ... :)
Cheers
Ganesh
On Mon, 8 Nov 2004 14:53:34 +0000, Ganesh Raja <ganesh.raja@xxxxxxxxx> wrote:
> Nisar,
>
> Did not Understand too much from your Post .. But How does all the
> things that you have talked about affect the way parallelism works ..
> Parallelism is CPU Bound and not disk bound ... U dictate if you want
> to Use Parallelism and then The ur Query/DML is Split across multiple
> processess that works out how to fetch data from the database and
> processes it.
>
> I am disagreeing here with irfhan also when he says that Multiple
> extents will give u chances of better parallelism. U can write a small
> testcase with a One Extent Table and See what happens .. U will still
> get Parallel Reads.
>
> The Only thing that has some effect on performance with Multiple
> Extent is the MBRC value since an Multi Block read cannot be done over
> multiple extents. [ U will never encounter this has a Problem]
>
> Apart from that i will never say that if you have 1000 Extents ur
> Query is Going to Perform badly and if you have 1 Extent it will
> perform any better. I need a test case from u to prove that the
> otherway.
>
> Extent has always been a Logical Grouping of Blocks and not a
> Physicall Grouping.
>
> My $0.02 and not my logic ... :)
>
> Rgds
> Ganesh
>
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