RE: ORA-01555 seems bogus

From: Goulet, Richard <>
Date: Mon, 8 Feb 2010 12:49:39 -0500
Message-ID: <>


    OH SH&^, I think we crossed wires. What I meant by "undo is the very last" is that the last thing you want to do is extend the undo space because the lack of undo is not the problem. Case in point, an SAP system that was always throwing ORA-01555 error on a specific report that took all day to process. The UNDO space was 10 times the size of the entire rest of the database because the BASIS Admin was always adding undo space in response to the error, yet the error remained.  

Dick Goulet
Senior Oracle DBA/NA Team Lead
PAREXEL International  

From: Kellyn Pedersen [] Sent: Monday, February 08, 2010 12:42 PM To:;; Goulet, Richard Subject: RE: ORA-01555 seems bogus

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. <>  

"Go away before I replace you with a very small and efficient shell script..."

  • On Mon, 2/8/10, Goulet, Richard <> wrote:
	From: Goulet, Richard <>
	Subject: RE: ORA-01555 seems bogus
	Date: Monday, February 8, 2010, 8:05 AM
	    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-----

org> [
org> ] On Behalf Of Herring Dave - dherri
	Sent: Saturday, February 06, 2010 10:10 PM

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)
  • 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
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	1501 Opus Pl | Downers Grove, IL, 60515 | U.S.A. |
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Received on Mon Feb 08 2010 - 11:49:39 CST

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