RE: .: .: How to track logfile switch

From: Bort, Guillermo <guillermo.bort_at_eds.com>
Date: Fri, 3 Oct 2008 11:43:55 -0500
Message-ID: <785A4E1EF4D9E745BAC909B7941BEC0094F281@usplm201.amer.corp.eds.com>


Alter system are not DML. DML are regular old fashioned SQL such as insert, update and delete. As someone else said in the list, every DML generates redo information and when the redo log file becomes full a log switch automatically occurs. This is basic transaction processing in Oracle. I would go with increasing the size of redo log buffer and maybe redo log files to have less than four log switches per hour during normal operation. And take it from there. I reckon the frequency of the problem will decrease greatly or the problem may even dissapear.  

HTH   Guillermo Alan Bort

EDS - ITO DBA Main Group  

From: Yavor Ivanov [mailto:Yavor_Ivanov_at_stemo.bg] Sent: Friday, October 03, 2008 1:00 PM
To: Bort, Guillermo; Bobak, Mark; oracle-l Subject: .: .: How to track logfile switch  

This sound promising. What DML could cause log switch (other than "alter system switch logfile" and "alter system archive log ...")?  

The issue happens during normal daily load.    

Regards,

Yavor Ivanov


: Bort, Guillermo [guillermo.bort_at_eds.com] : 03 2008 . 18:45
: Yavor Ivanov; Bobak, Mark; oracle-l
: RE: .: How to track logfile switch

It may be silly to mention this, however log switches can be caused by valid dml processing not just alter system switch logfile. I've found that increasing redo log size and redo log buffer often helps lower the number of Checkpoint not Complete. Do you notice this issue during periods of high transaction load or batch load? Also, do you have fast_start_mttr_target set to a static value?  

HTH   Guillermo Alan Bort

EDS - ITO DBA Main Group  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Yavor Ivanov Sent: Friday, October 03, 2008 12:36 PM
To: Bobak, Mark; oracle-l
Subject: .: How to track logfile switch  

 The value of ARCHIVE_LAG_TARGET is 0  

Unfortunately the message "Thread X cannot allocate new log, sequence XXXX" is sometimes followed by "Checkpoint not complete". So I cannot ignore it easily. Yesterday there was a short but noticeable database hang at the same time when this happened.  

Regards,

Yavor Ivanov

[SNIP]

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Received on Fri Oct 03 2008 - 11:43:55 CDT

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