RE: ORA-01555 seems bogus

  • From: Kellyn Pedersen <kjped1313@xxxxxxxxx>
  • To: Dave.Herring@xxxxxxxxxx, oracle-l@xxxxxxxxxxxxx, Richard.Goulet@xxxxxxxxxxx
  • Date: Mon, 8 Feb 2010 09:42:03 -0800 (PST)

Now Dick, 
I agree that the overall culprit is often exactly what you have detailed below, 
but I think it is important to see that what you *think* is being used by your 
statement might be very different in reality when executed in whole-  as part 
of that one procedure, etc...  
I think starting with undo is perfectly acceptable to see what the database has 
allocated towards the process, then proceed back, into the statement(s) in 
question to see where the logic is causing the issue or what other processes 
might be hampering the one that's been identified as the problem... :)

Kellyn Pedersen
Multi-Platform DBA
I-Behavior Inc.
http://www.linkedin.com/in/kellynpedersen
www.dbakevlar.blogspot.com
 
"Go away before I replace you with a very small and efficient shell script..."

--- On Mon, 2/8/10, Goulet, Richard <Richard.Goulet@xxxxxxxxxxx> wrote:


From: Goulet, Richard <Richard.Goulet@xxxxxxxxxxx>
Subject: RE: ORA-01555 seems bogus
To: Dave.Herring@xxxxxxxxxx, oracle-l@xxxxxxxxxxxxx
Date: Monday, February 8, 2010, 8:05 AM


Dave,

    An ORA-01555 is never bogus, but very misleading as you've found out.  OK, 
so the query in question is part of a package.  Is the package called from some 
application that's doing a "commit across a cursor", or is the package doing it 
internally?  Lots of places to look and undo is the very last.


Dick Goulet
Senior Oracle DBA/NA Team Lead
PAREXEL International

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Herring Dave - dherri
Sent: Saturday, February 06, 2010 10:10 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: ORA-01555 seems bogus

Folks, I've got a curious situation where we're getting regular ORA-01555 
errors yet they don't seem correct.  First a few things on the set up:

* 4-node RAC (+ 4-node RAC DG)
* 10.2.0.2
* RHEL 8 x 64GB servers

The query returned in the error is doing a full scan of a 3,100 row table, 
which takes less than 1 sec to complete.  I've tried the same query repeatedly 
and it always takes less than one second, even when trying it while ORA-01555 
errors are being returned saying that query is failing elsewhere.  The query is 
run 10,000+ times per day, always run from the same node.

The ORA-01555 error lists this query as having a duration of around 12,000 
seconds each time, which from what I can tell is impossible.  Again, it's a 
3,100 row table, no parallelism, 1 index (which isn't used by this query).  I 
checked LAST_ANALYZED and the table hasn't been analyzed in 4 days.  I checked 
DBA_TAB_MODIFICATIONS and it's had around 200 DML's since it was analyzed, but 
the last of which was 2 days ago.

So is Oracle returning the wrong query?  Is the ORA-01555 bogus?  Checking 
GV$UNDOSTAT, SSOLDERRCNT matches the # of ORA-01555 we're seeing (87 today, all 
the same query).  All instances have the same UNDO_RETENTION (3600) and 
similarly sized undo tablespaces.

Any clues how to catch the trouble making queries?

Dave Herring  | DBA, Global Technology Services
A c x i o m  C o r p o r a t i o n
630-944-4762 office | 630-430-5988 cell | 630-944-4989 fax
1501 Opus Pl | Downers Grove, IL, 60515 | U.S.A. | www.acxiom.com
Service Desk: 888-243-4566, https://servicedesk.acxiom.com, GSCA@xxxxxxx


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