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 >