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Oracle 11g New Features

Online Oracle Training

 

Oracle 11g: How to use the Database Replay at Oracle 11g database

 

 

What is the database replay?
Simply, the database replay process captures a sequence of Oracle DML in a file in a capture directory. Then you can replay the file against the same database or a different one to execute the same DML.
 
Why do I need to do that?
You may use this to test performance problem at your environment. Assuming that you want to change a parameter at your production database but you have no idea about its result. You can capture a peak time DML from your production and replay it as many you want at your test environment.
 
How do I do that?
Create capture directory
  $ cd /home
  $ mkdir dircapture
 
Create a directory object in the database
  SQL> CREATE DIRECTORY dircapture AS "/home/dirdirectory";
 
One hour before your peak time start capture using the following procedure. We are using NULL for duration so we stop the capture when we want.
 

SQL> BEGIN
    DBMS_WORKLOAD_CAPTURE.START_CAPTURE (NAME => "dml_capture",
    DIR => "DIRCAPTURE",
    DURATION => NULL);
    END;
    /
 
Once you pass the peak time or you are satisfy. You can stop the capture using the following procedure.
 

SQL> BEGIN
      DBMS_WORKLOAD_CAPTURE.FINISH_CAPTURE;
      END;
      /
 
If replay performs on different server, FTP the file into created replay directory.


Assuming that you have FTP the dml_capture file with a new name dml_replay:
To create replay directory:
  $ cd /home
  $ mkdir dirreplay
 
Create a directory object in the database
  SQL> CREATE DIRECTORY dirreplay AS "/home/dirreplay";
 
Tell your database where that file is: 
Notice that your directory must be upper case.


SQL> BEGIN
    DBMS_WORKLOAD_REPLAY.INITIALIZE_REPLAY (REPLAY_NAME=>"dml_reply",

    REPLAY_DIR => "DIRREPLAY";
    END;
    /
 
Then start replay process.
   SQL> EXEC DBMS_WORKLOAD_REPLAY.START_REPLAY();
 
Check your performance and compare your benchmark.

 

 

Good Luck!

 

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