RE: FTS not reaching multiblock count value

From: Connor McDonald <hamcdc_at_yahoo.co.uk>
Date: Sat, 22 Sep 2001 07:30:09 -0700
Message-ID: <F001.003959C5.20010922074517@fatcity.com>

And just to add, even the SSTIOMAX is "unachievable" if other things get in the way.

For example, on Solaris 8.1 if you set
db_file_multiblock_read_count to (say) 1000 on an 8k blocksize, you'll see in v$parameter sizes it down to 128 (indicating a 1M SSTIOMAX).

But do a full table scan with the 10046 trace and you'll typically the best obtained in 16 or 32, mainly because of the default Solaris maxphys setting, or file system restrictions, or Veritas vxio max size restrictions.

You've got to get them all correct to get the full SSTIOMAX that Oracle can offer.

hth
connor

• K Gopalakrishnan <kaygopal_at_yahoo.com> wrote: > Rahul,
  >
  > Actually there is a kernel constant SSTIOMAX which
  > overrides the db_file_multiblock_read_count if you
  > set that to higher values than SSTIOMAX.
  >
  > ANd this SSTIOMAX is very much OS/version/hardware
  > dependent. What is your block size? Is it 2K (since
  > you have set db_file_multiblock_read_Ccount to 32).
  >
  > How are you tracing that value? Have you set the
  > event 10046 or just selecting from the
  > V$session_event?
  >
  > Best Regards,
  > K Gopalakrishnan
  > Bangalore, INDIA
  >
  >
  

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Received on Sat Sep 22 2001 - 09:30:09 CDT