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Sunday, November 22, 2015

Journals & Retrieve Data from Journals

Journaling on IBM i:


On IBM i, Journaling means process of recording an object's activity.

When it comes to journaling of Physical file, It records Open/Close/Write/Update/Delete Operations on Physical file.

How to Start Journaling:


1.      Use the Create Journal Receiver (CRTJRNRCV) command to create a journal receiver.

The journal receiver is where the journal entries are actually recorded. The journal "connects" the receiver to the file.

Also, you should put journal receivers in the same library as the file.

2.      Create a journal. Use the Create Journal (CRTJRN) command to create a journal and specify the receiver created in step 1.

Although you can journal multiple files to the same journal, you will generally want to have a journal "serving" a single file.

3.      Start journaling the file. This is done by using the Start Journal Physical File (STRJRNPF) command.

This is how you associate a file to a journal. Once the association is made, the system will record in the journal receiver a copy of any record added, updated or deleted from the file.

Other activity, such as when the file is opened and closed, can also be recorded in the journal receiver if you choose by selecting the appropriate options on the STRJRNPF command.

Retrieve Data from Journal:


You would get a scenario where records were deleted wrongly or update happened wrongly, You would need to retrieve the data back.

Below are the steps to be followed in order to retrieve data from Journal.

1.     Issue DSPJRN Command by specifying Journal Name & Journalled Physical File Name.

You might want to consider giving specific Journal Receiver Name. By default it would be current Receiver.

2.    Create a Copy of Physical File to include Journal Fields along with Original Physical File Fields.

3.    Use CPYF Command with FMTOPT(*NOCHK) from DSPJRN Outfile to JR file with Journal fields.

Example:

DDS of Physical File (TESTFILE):

     A          R TESTFR                                                        
     A            TSFLD1        10A                                             
     A            TSFLD2        10A                                             
     A            TSFLD3        10A                                             
     A            TSFLD4        10A                                             

DDS of JR File with Journal Fields (JRTESTFILE):

     A          R JRTESTFR                                                      
     A            JOENTL         5S 0                                           
     A            JOSEQN        10S 0                                           
     A            JOCODE         1A                                             
     A            JOENTT         2A                                             
     A            JODATE         6A                                             
     A            JOTIME         6S 0                                           
     A            JOJOB         10A                                             
     A            JOUSER        10A                                             
     A            JONBR          6S 0                                           
     A            JOPGM         10A                                             
     A            JOOBJ         10A                                             
     A            JOLIB         10A                                             
     A            JOMBR         10A                                             
     A            JOCTRR        10S 0                                           
     A            JOFLAG         1A                                             
     A            JOCCID        10S 0                                           
     A            JOINCDAT       1A                                             
     A            JOMINESD       1A                                             
     A            JORES          6A                                             
     A            TSFLD1        10A                                             
     A            TSFLD2        10A                                             
     A            TSFLD3        10A                                             
     A            TSFLD4        10A                                             

Issue DSPJRN Command on TESTFILE:

DSPJRN JRN(LIBRARY/TESTJRN) FILE((LIBRARY/TESTFILE)) OUTPUT(*OUTFILE) OUTFILE(LIBRARY/JROUTFILE)

Use CPYF Command to get formatted Output of file data.

CPYF FROMFILE(LIBRARY/JROUTFILE) TOFILE(LIBRARY/JRTESTFILE) MBROPT(*ADD) FMTOPT(*NOCHK)

You would need to check the scenario where you need to recover the data and can query based on requirement.


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