RE: explain plan, can you explain this?
Date: Thu, 10 Jan 2008 14:30:28 +0200
John, are you sure that statspack reports sql statistics cumulatively?
As far as I know it lists them as delta values between the end snapshot and the begin snapshot. The package STATSPACK gets the current values from v$sql and stores them in stats$sql_summary and spreport.sql gets the difference between snapshots. From my spreport.sql from a 188.8.131.52 home:
... lpad(to_char((e.buffer_gets - nvl(b.buffer_gets,0))
,'99,999,999,999') ,15) ... from stats$sql_summary e , stats$sql_summary b
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of John Kanagaraj Sent: Thursday, January 10, 2008 6:09 AM To: dannorris_at_dannorris.com
Cc: Oracle L
Subject: Re: explain plan, can you explain this?
> The very interesting part is that in a one-hour statspack, this
> generates 30 mil buffer gets, executed 111,388 times (about 273 buffer
> per exec). When combined with the facts below, it becomes a puzzler:
This is only slightly related to the issue, but STATSPACK's SQL is a capture of V$SQL "as-is" when the snapshot took place. SPREPORT does NOT perform a Diff as it does with other stats (i.e. end_stat - begin_stat). The 111,388 executions is *cumulative* since that SQL was last loaded/parsed. This is apparent if you look at the STATSPACK source at $OH/rdbms/admin/spcpkg.sql.
You should look at Tim G's "sphistory.sql" to determine the periodic progression of execution and other stats for a given SQL.
-- 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 ** -- http://www.freelists.org/webpage/oracle-l -- http://www.freelists.org/webpage/oracle-lReceived on Thu Jan 10 2008 - 06:30:28 CST