RE: db_file_multiblock_read_count causing full scans to takelonger?

  • From: "Kevin Closson" <kevinc@xxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 19 Dec 2006 13:03:07 -0800

Is this direct I/O or a filesystem? Could the filesystem
be firing off some uneccessary read-aheads when you do large
dfmbrc but not when you are nibbling with smaller multiblock request?

>>>-----Original Message-----
>>>From: oracle-l-bounce@xxxxxxxxxxxxx 
>>>[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Kevin Lidh
>>>Sent: Tuesday, December 19, 2006 12:58 PM
>>>To: Allen, Brandon
>>>Cc: oracle-l@xxxxxxxxxxxxx
>>>Subject: RE: db_file_multiblock_read_count causing full 
>>>scans to takelonger?
>>>Well, that's what contributed to my confusion. In my trace 
>>>files, which are 9i so slightly different:
>>>WAIT #1: nam='db file scattered read' ela= 21614 p1=6 p2=3979 p3=126
>>>--> 126 blocks = 21614

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