Re: Clarification of DSPFD output

Logical reads is a number of HLL requests to system for database records.
When blocking is used, this number can be significantly less than actual
number of records processed.
Physical reads are those of above that could not be satisfied from main
storage and required access to DASD.

Best regards
    Alexey Pytel



Pete Massiello <pmassiello@os-solutions.com> on 04/30/99 07:22:34 AM

Please respond to MIDRANGE-L@midrange.com

To:   MIDRANGE-L@midrange.com
cc:    (bcc: Alexei Pytel/Rochester/IBM)
Subject:  Re: Clarification of DSPFD output





I believe the physical read is a read that actually goes out to disk to get
the
record, where the logical read in the statistics below are reads that the
record
was found in a page that was already in memory, and therefore a new read to
disk
was not required to be performed.

    By the way, what gives with the disclaimer at the end of your message,
are
you a lawyer masking as an AS/400 programmer?

Pete

Kris Vaidyanathan wrote:

> When you do a DSPFD on a file on the there is some info that I need
> clarification on.
> I have a file that says the following..
>
> Open Operations......................................77,875
> Close Operations......................................77,875
> Write Operations.......................................16,940
> Update Operations....................................0
> Delete Operations.....................................16,940
> Logical Reads........................................513,079,190
> Physical Reads......................................201,016,762
>
> This is a highly volitile file used for passing trigger info around and I
> understand the Open Closes and Write/Update/Delete numbers.
> What do the Logical and Physical reads mean. This is an unkeyed
physicalwith
> no logicals etc.
>
> krisV
> ______________________________________
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--
Pete Massiello
OS Solutions International
Phone: (203)-744-7854  Ext 11.
http://www.os-solutions.com
mailto:pmassiello@os-solutions.com


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