Re: Why sometime redo log switch very fast?

On Sun, 6 Feb 2005 16:47:40 +0800, "music4" <music4_at_163.net> wrote:

>> A redolog switch every minute is really undesirable, let alone every
>> 20 seconds.
>> If you have a redolog switch every 20 seconds it simply measn your
>> application is generating three times as much redolog volume.
>> You can easily find out what is going on using logminer.
>>
>> Oracle doesn't have any mechanism to increase the number of redolog
>> switches.
>>
>>
>> --
>> Sybrand Bakker, Senior Oracle DBA
>
>Sybrand,
>
>Thanks for your answer. But the problem is from our applicaton's log, we am
>sure our application did generate too much redolog. So I want to check what
>generated too much redo?
>
>And what's "logminer"? I cannot find it under $ORACLE_HOME/bin.
>
>Evan
>
>

Logminer is a pl/sql utility, you can apply to online and archived redologs
The utility reads the logs and populates v$logmnr_contents

You populate this by using
dbms_logmnr.add_file

and you start working with them using
dbms_logmnr.start_logmnr

after that you can select from v$logmnr_contents

In it's bare form it won't however list table names and colum names, you'll need
dbms_logmnr_d
to create a copy of the datadictionary in flat file format. More details in Appendix A of Thomas Kyte's Expert One on One book and of course in the Oracle Supplied Packages reference.

Hth

--
Sybrand Bakker, Senior Oracle DBA