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Re: Redo Log maintenance

From: Howard J. Rogers <howardjr_at_www.com>
Date: Thu, 11 Oct 2001 16:26:21 +1000
Message-ID: <3bc53d1e@news.iprimus.com.au>


Not wishing to be unkind, but your confusion is on a fundamental and pretty basic feature of Oracle architecture.

For a specific response to your query, you could do worse than visit http://www.geocities.com/howardjr2000 and visit the 'BOOKS' page. There's a short paper I wrote there on Oracle architecture.

If you don't fancy that, you'll really have to invest in at least a DBA basics book, such as Oracle Press produce. It's fair enough to*say* 'redo' when you mean 'rollback', and I do it all the time, but to confuse the concepts is going to cause unending grief, and you need to get it sorted pronto.

Regards
HJR "Wade Chy" <wchy65_at_hotmail.com> wrote in message news:36df3e33.0110101313.4c65d647_at_posting.google.com...
> Hi All
> I am helping somebody maintain the redo log. The database has 2 redo
> log files 1 mb each. They are filling up quick. I have to create 2
> more. If I just create 2 more log files, will it work or I have to
> create the rollback tablespaces and segments for it?
> The reason I am confused about it is because I tried to create a
> database with GUI Oracle Database Configuration Assistant. I saved the
> scripts for creating the database later. It saved 1 batch file and 4
> sql scripts. The first script creates the database with 2 log files
> sized 1024 k with the following statements:
>
> CREATE DATABASE app
> LOGFILE 'E:\test_data\app\redo\redo01.log' SIZE 1024K,
> 'E:\test_data\app\redo\redo02.log' SIZE 1024K
> MAXLOGFILES 32
> MAXLOGMEMBERS 2
> MAXLOGHISTORY 1
> DATAFILE 'E:\test_data\app\system01.dbf' SIZE 10M REUSE
> MAXDATAFILES 254
> MAXINSTANCES 1
> CHARACTER SET WE8ISO8859P1
> NATIONAL CHARACTER SET WE8ISO8859P1;
>
> And the the 2nd script that creates the tablespaces has the following
> statements:
>
> REM ********** TABLESPACE FOR ROLLBACK **********
> CREATE TABLESPACE RBS DATAFILE 'E:\test_data\app\rbs01.dbf' SIZE 12M
> REUSE
> DEFAULT STORAGE ( INITIAL 1024K NEXT 1024K MINEXTENTS 2 MAXEXTENTS 121
> PCTINCREASE 0);
> ALTER DATABASE DATAFILE 'E:\test_data\app\rbs01.dbf' AUTOEXTEND ON;
>
>
> CREATE PUBLIC ROLLBACK SEGMENT RB0 TABLESPACE RBS
> STORAGE (INITIAL 100K NEXT 250K);
> CREATE PUBLIC ROLLBACK SEGMENT RB1 TABLESPACE RBS
> STORAGE (INITIAL 100K NEXT 250K);
> ALTER ROLLBACK SEGMENT "RB0" ONLINE;
> ALTER ROLLBACK SEGMENT "RB1" ONLINE;
>
> It creates a rollback tablespace and 2 rollback segments. What is the
> relation or difference between the log files and the rollback
> tablespce? Which one does the transactions use, the 'rbs01.dbf' or the
> 'E:\test_data\app\redo\redo01.log' SIZE 1024K,
> 'E:\test_data\app\redo\redo02.log' SIZE 1024K?
> Also is there any data dictionary view I can look at to find out if
> the redo log is filling out quickly and there are a lot of log
> switches. I am trying to find out if the smaller logfiles and low
> number of logfile is creating a performance problem.
> Please help.
> Thank you in advance.
Received on Thu Oct 11 2001 - 01:26:21 CDT

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