Comments on: Oracle Troubleshooting with Snapper – detecting who’s causing excessive redo generation

By: High Redo Logs or Archives? « Anjul Sahu's Oracle Blog

High Redo Logs or Archives? « Anjul Sahu's Oracle Blog — Tue, 23 Aug 2011 13:52:04 +0000

[...] found the article by Tanel Poder on the same, and his snapper script is quite useful in identifying the users generating huge amount [...]

By: Anjul

Anjul — Tue, 23 Aug 2011 13:48:09 +0000

Excellent Tool – It surprises me everyday :-)

Thanks!

By: Tanel Poder

Tanel Poder — Sun, 11 Oct 2009 11:24:36 +0000

Well if you describe V$LOGMNR_CONTENTS you see there’s a session_id column in there, this gives you session info. And with something like ASH or manual v$session history you could see which dml statements these sessions did at the time. There is no direct way though to link redo generation to a SQL statement as Oracle doesn’t measure redo generation by SQL statement.

By: Dakshin

Dakshin — Sat, 10 Oct 2009 11:34:50 +0000

Thanks. But how do I know which sessions / SQLs were causing more redo? Is it that I go through the whole day’s transactions by txn id and try to gauge their impact ? (Mainly look at DML statements)

By: Tanel Poder

Tanel Poder — Fri, 09 Oct 2009 15:35:36 +0000

Yes, you need to access the old archivelogs from past with LogMiner. Read the documentation about DBMS_LOGMNR and V$LOGMNR_CONTENTS

By: Dakshin

Dakshin — Fri, 09 Oct 2009 09:48:24 +0000

Hi Tanel,

Is there a way to know why my DB was generating 3 times the ‘normal’ redo 3 days back? Want to diagnose so that I can prevent, if possible, such occurrences in the future. Thanks.

By: Oracle Session Snapper – real-time session-level performance stats for DBAs | Tanel Poder's blog: Core IT for Geeks and Pros

Tue, 11 Aug 2009 01:36:58 +0000

[...] http://blog.tanelpoder.com/2008/05/30/oracle-troubleshooting-with-snapper-detecting-whos-causing-exc... [...]

By: tanelp

tanelp — Mon, 07 Jul 2008 08:16:03 +0000

Snapper doesn’t have this functionality for two reasons:

1) i haven’t figured out an easy way to persist the snapshot information *without having to create any stored objects in db*

2) my Sesspack tool has this functionality and more..

By: CJ

CJ — Mon, 07 Jul 2008 08:08:13 +0000

Hi Tanel,

Probably my earlier post didn’t make sense. I will try to simplify the question I was asking:

Is it possible to use the snapper tool such that you generate a snapshot before starting the process, take another snapshot when the process ends and get the report on the changed stats?

By: CJ

CJ — Mon, 30 Jun 2008 17:49:54 +0000

Hi Tanel,

First of all, congrats and thanks for a brilliant weblog and website.

The snapper tool is quite good, but I am finding it a bit ‘different’. I am used to using runstats, so it might just be a case of getting familiarized.

I open 2 SQL windows. I take snap session A from session B, and the run the problematic piece of code in session A. Once the code finishes, I take another snap in session A and print the deltas. This is normally good enough for me, and only in rare cases would I require more frequent snaps.

Right I don’t think now you can get snapper to function in the above-mentioned way, but correct me if I am wrong.