RE: explain plan, can you explain this?

  • From: "Yasin Baskan" <yasin.baskan@xxxxxxxxxxxxxxxx>
  • To: "Andrew Kerber" <andrew.kerber@xxxxxxxxx>, <john.kanagaraj@xxxxxxxxx>
  • Date: Fri, 11 Jan 2008 11:04:51 +0200

Andrew, AWR reports delta values, not cumulative statistics.

 

It reports the delta values from the columns of dba_hist_sqlstat like
buffer_gets_delta.

 

Here is a part of an sql run by a 10.2 awrrpt.sql

 

...

sum(disk_reads_delta) dskr, sum(executions_delta) exec,

 

                      sum(cpu_time_delta) cput, sum(elapsed_time_delta)
elap

...

from dba_hist_sqlstat

                  where dbid

      = :dbid

                    and instance_number = :inst_num

 

          and :bid            < snap_id

                    and snap_id

   <= :eid

               group by sql_id)

...

 

From: Andrew Kerber [mailto:andrew.kerber@xxxxxxxxx] 
Sent: Thursday, January 10, 2008 7:57 PM
To: john.kanagaraj@xxxxxxxxx
Cc: Yasin Baskan; dannorris@xxxxxxxxxxxxx; Oracle L
Subject: Re: explain plan, can you explain this?

 

And then, you have to do it again for AWR.  AWR does report cumulative
statistics.

On Jan 10, 2008 11:36 AM, John Kanagaraj <john.kanagaraj@xxxxxxxxx >
wrote:

> John, are you sure that statspack reports sql statistics cumulatively?


Yasin and Allen,

You are right: My bad. STATSPACK indeed does report the differences.
This myth of mine was self-created, probably from early days of
STATSPACK. Thank you for setting me right. This reminds me once more 
to re-validate everything I know.

Regards,

--
John Kanagaraj <><
DB Soft Inc
http://www.linkedin.com/in/johnkanagaraj 
http://jkanagaraj.wordpress.com (Sorry - not an Oracle blog!)
** The opinions and facts contained in this message are entirely mine
and do not reflect those of my employer or customers ** 
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-- 
Andrew W. Kerber

'If at first you dont succeed, dont take up skydiving.'

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