RE: db file scattered read

Mladen,

I guess the rdbms kernel will be passing the startblock-stop block addresses and will be passing to the readv (or pread?) system calls. A single multiblock read can not read two different sets (!) of contiguos blocks.. Or I am thinking in the different direction??

Best Regards,
K Gopalakrishnan  

-----Original Message-----
Mladen
Sent: Monday, March 17, 2003 7:45 AM
To: Multiple recipients of list ORACLE-L

How can you tell that DB_FILE_MULTIBLOCK_READ will not span extents? I was unable to confitrm that on Metalink.

> -----Original Message-----
> From: Hemant K Chitale [mailto:hkchital_at_singnet.com.sg]
> Sent: Monday, March 17, 2003 9:44 AM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: db file scattered read
>
>
>
> If 14706+3 is one extent and another extent begins at 14710,
> it will NOT read
> 14706+8. A DB_FILE_MULTIBLOCK_READ will not span extents.
> Hemant
>
> At 09:04 AM 14-03-03 -0800, you wrote:
> >Here is a part of trace file . I am finding that oracle is
> trying to read
> >8 or 3 or 7 blocks at a time . But block numbers are all
> sequential i.e.
> >it will read 3 blocks starting from 14706 and then 8 blocks
> starting from
> >14710 ( 14706+3 ). Why it doesn't read 8 blcoks always it
> multi_block_read
> >is set to 8 ? Any Idea .
> >Also what is ela=1 ,does it mean elapsed time is 1 sentisec ?
> >
> >
> >
> >WAIT #32: nam='db file scattered read' ela= 0 p1=4 p2=14706 p3=3
> >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=14710 p3=8
> >WAIT #32: nam='db file scattered read' ela= 2 p1=4 p2=14718 p3=8
> >WAIT #32: nam='db file scattered read' ela= 0 p1=4 p2=14727 p3=3
> >WAIT #32: nam='db file scattered read' ela= 0 p1=4 p2=14731 p3=7
> >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=14739 p3=3
> >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=14744 p3=8
> >WAIT #32: nam='db file scattered read' ela= 1 p1=4 p2=129784 p3=8
> >
> >
> >Thanks
> >-ak
>
> Hemant K Chitale
> My personal web site is : http://hkchital.tripod.com
>
>
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> Please see the official ORACLE-L FAQ: http://www.orafaq.net
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> Author: Hemant K Chitale
> INET: hkchital_at_singnet.com.sg
>
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-- 
Author: K Gopalakrishnan
  INET: kaygopal_at_yahoo.com

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