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log file sync [message #64981] Mon, 22 March 2004 21:28 Go to next message
Anatol Ciolac
Messages: 113
Registered: December 2003
Senior Member
Hello folk!

I have a excessive amount of 'log file sync' waits on my database(30-35%). In documentation are write that this waitevent occur when the session are commit. I have traced some sessions on database and has seen that this waitevent occur not only after commits but also after exec and fetch operations. Can anyone explain to me why this occur.

 
Re: log file sync [message #64988 is a reply to message #64981] Wed, 24 March 2004 09:17 Go to previous message
Thiru
Messages: 1089
Registered: May 2002
Senior Member
Usually log_file_syncs happen on commits and when DBWR waits for the LGWR to flush the redo entries corresponding to the recent changes.

These are Selects and not Updates,deletes,commits ? How about posting a test case , in sqlplus, with sql_trace enabled.

For testing purposes,can do you a full table scan on all the tables used by this query and then observe if you still have log file syncs on the exec/fetch calls of your queries ? I am trying to eliminate something as a possible cause.

-Thiru
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