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Solaris - db_file_multiblock_read_count

From: Jeff Wiegard <JWIEGARD_at_ngwmail.des.state.mn.us>
Date: Mon, 19 Nov 2001 13:48:41 -0800
Message-ID: <F001.003C8D7B.20011119132017@fatcity.com>

Hi.

I was hoping for some confirmation here.

I'm running 8.0.5 on Solaris 2.7, with block size set to 8192. There is no 'maxphys' parameter in /etc/system.

After some testing, I've decided to set the db_file_multiblock_read_count = 24, based on the following:

  1. SQL> alter session set db_file_multiblock_read_count = 1000;
  2. select value from v$parameter where name = 'db_file_multiblock_read_count';
      This gave me a value = 128
        

3. alter session set events '10046 trace name context forever, level 8';

4. select /*+ FULL(t) */ count(*) from sys.source$ t;

The trace file gave me the following:

WAIT #1: nam='db file scattered read' ela= 0 p1=1 p2=660 p3=25
WAIT #1: nam='db file scattered read' ela= 0 p1=1 p2=1167 p3=25
WAIT #1: nam='db file scattered read' ela= 0 p1=1 p2=1207 p3=25
WAIT #1: nam='db file scattered read' ela= 0 p1=1 p2=1272 p3=25
WAIT #1: nam='db file scattered read' ela= 0 p1=1 p2=1312 p3=25

So then setting db_file_multiblock_read_count to 24 would be about right ... right?

Thanks,

Jeff

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Author: Jeff Wiegard
  INET: JWIEGARD_at_ngwmail.des.state.mn.us

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