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RE: Memory stats on 8i

From: Khedr, Waleed <Waleed.Khedr_at_FMR.COM>
Date: Thu, 19 Feb 2004 20:45:38 -0500
Message-ID: <D91D9D5A73FC694BBC52F1EB26AD410FA2E4BD@MSGBOSCLD2WIN.DMN1.FMR.COM>


Jared, I believe this is the historical sum (since the instance startup) for the stats that show up in v$sesstat.
If you need the numbers that reflect the current instance condition, use sum(...) from v$sesstat.

Regards,

Waleed

-----Original Message-----

From: Jared.Still_at_radisys.com [mailto:Jared.Still_at_radisys.com] Sent: Thursday, February 19, 2004 8:31 PM To: oracle-l_at_freelists.org
Subject: Memory stats on 8i

Dear list,
While trying to retrieve some useful memory metrics from statspack data, I discovered
a couple of disconcerting problems with both statspack and v$sysstat.

Here's an example of querying stats$sysstat for "session pga memory" and "session
 uga memory":

NAME     SNAP_TIME                       BYTES

-------- ---------------- --------------------
Sess Mem 02/12/2004 14:15 5,283,446,030,900 02/12/2004 14:30 5,283,942,124,164 02/12/2004 14:45 5,284,433,165,904 02/12/2004 15:00 5,284,911,244,452 02/12/2004 15:15 5,285,416,815,816 02/12/2004 15:30 5,285,913,292,596 02/12/2004 15:45 5,286,408,666,940 02/12/2004 16:00 5,286,892,600,984 02/12/2004 16:15 5,287,399,692,508 02/12/2004 16:30 5,287,867,287,248 02/12/2004 16:45 5,288,350,093,876 02/12/2004 17:00 5,288,820,633,944 02/12/2004 17:15 5,289,315,381,036 02/12/2004 17:30 5,289,786,863,136

I doubt many windows boxes carry that much RAM around with them.

Thinking it might be a problem with statspack, a query on v$sysstat was then run:

17:22:10 CIMORAPROD - perfstat_at_dal3 SQL> l   1 select class,name, value
  2 from v$sysstat
  3 where name like '%&&statname%'
  4* order by class,name
17:22:15 CIMORAPROD - perfstat_at_dal3 SQL> /

CLASS NAME                                                    VALUE

----- ---------------------------------------- --------------------
1 session pga memory 5,604,491,571,208 session pga memory max 5,631,672,698,788 session uga memory 10,122,362,780 session uga memory max 94,136,262,424 64 sorts (memory) 145,100,842

5 rows selected.

17:22:16 CIMORAPROD - perfstat_at_dal3 SQL>

No joy. Turns out this is due to a bug that was not fixed until some version of 9i, and ostensibly
backported to 8.1.7.2. Apparently not, as this is an 8.1.7.4.1 database.

No problem, I think, just get the data from stats$sesstat;

17:25:02 CIMORAPROD - perfstat_at_dal3 SQL> select * from stats$sesstat;

no rows selected

17:25:22 CIMORAPROD - perfstat_at_dal3 SQL>

Even less joy.

It seems that no level of statspack snapshot will populate the session tables.
A metalink search turns up the problem, but no solution.

This doesn't work in 9i either BTW.

If anyone has encountered this and found a work around, would you mind sharing.

Oh yeah, this is on top of the bug in 8.1.6 that gives highly erroneous CPU numbers if
you happen to be using DBA_JOBS. ( a different database )

Thanks,

Jared

PS. The network stats appear to be good.



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Received on Thu Feb 19 2004 - 19:45:38 CST

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