Re: 9i / 9iRAC : Segment_Space_Management AUTO, with LOB

[Mogens Nørgaard]

It would appear we're looking into yet another hit ratio, namely the ASS Hit Ratio. Used to be rather high in my younger days.

Mogens

Jonathan Lewis wrote:

Depending on your circumstances, ASS Management
can eliminate severe contention on the freelists / freelist
groups area.  However, because Oracle is overgenerous
with its allocation of bitmap blocks (which may turn
out to be in excess of 1% of your database), you
may end up thrashing your system because most of
your buffer space is flooded with hot BMBs and the
data has to keep thrashing on and off disk.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

Coming soon a new one-day tutorial:
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-----Original Message-----
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
Date: 19 December 2002 17:51


  

We were the other way around in our testing lately:-)

We turned on auto space management to remove the contention.
    

Afterwards-we
  

removed quite a bit of header block/free list contention..

anyway, more tests to follow

-----Original Message-----
Sent: Thursday, December 19, 2002 10:09 AM
To: Multiple recipients of list ORACLE-L



As part of a RAC benchmark with 9.2 we had faced severe LOCKING
on setting segment space management AUTO & had to REMOVE it

HTH