Re: Effect of number of extents on Oracle I/O performance
Date: Sun, 15 Mar 2009 09:39:32 +0100
What were the old extent sizes?
On Sat, Mar 14, 2009 at 10:23 AM, Nuno Souto <dbvision_at_iinet.net.au> wrote:
> Mark W. Farnham wrote,on my timestamp of 14/03/2009 10:58 AM:
> 2) When the extent size is very small (smaller than a multiblock read)
>> in cases where a multiblock read is interrupted by the extent boundary
>> time, then many small extents can be noticed. (If the extents are even a
>> reasonable size, then the collision interrupting a multiblock read quickly
>> becomes an infrequent event in a full table scan and the overhead
>> in the noise.
> Seen this in some of the tablespaces in our DW. Unexplained slowdowns of
> FTS. Since then I've changed them to UNIFORM with size 50M or 100M,
> depending on the tables kept there. No more problems.
> Nuno Souto
> in sunny Sydney, Australia