RE: wait event puzzler

For the record, 'db file sequential read' isn't ALWAYS a single-block read. There are cases in which you can see 'db file sequential read' events with p3>1. It happens (well, happened) when the kernel reads from a data file directly into a user's non-shared process space (not the SGA). It used to happen in Oracle7.3 when reading sort segments from disk into a PGS. Nowadays, these reads are done with the event 'direct path read'.

It is true that 'db file scattered read' will never have p3=1.

Cary Millsap
Hotsos Enterprises, Ltd.
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-----Original Message-----
Wolfgang Breitling
Sent: Wednesday, June 11, 2003 3:55 PM
To: Multiple recipients of list ORACLE-L

Yes, 'db file sequential read' is always a single block read. It is 'db file scattered read' which is <= DB_FILE_MULTIBLOCK_READ_COUNT

At 10:35 AM 6/11/2003 -0800, you wrote:
>A SINGLE block? I was convinced that it was <=
DB_FILE_MULTIBLOCK_READ_COUNT
>blocks.
>Are you sure?
>
>Mladen Gogala
>Oracle DBA
>Phone:(203) 459-6855
>Email:[EMAIL PROTECTED]
>
>
>-----Original Message-----
>Sent: Wednesday, June 11, 2003 2:19 PM
>To: Multiple recipients of list ORACLE-L
>
>
>Dennis:
>
>THe event 'db file sequential read' is NOT always an INDEX Scan. It is
>just a single block read which TYPICALLY happens during an INDEX scan.
>The word 'TYPICALLY' is the key here.
>
>
>
>Best Regards,
>K Gopalakrishnan

Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

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