Expanding only root segments from length 255 to 275

rakesha.hg · Posted: Wed Sep 12, 2012 6:00 pm

hi All,

I have a IMS file with following structure.

Nic Clouston · Posted: Wed Sep 12, 2012 6:40 pm

You are trying to access the same database in 2 different formats at the same time? I belive the usual route to convert a DB is to read the old DB wrting the unloaded segments in the new format the load the data to the new DB with the new DBD. Once everything is hunky-dory - delete the old DB.

rakesha.hg · Posted: Wed Sep 12, 2012 7:00 pm

thanks for the reply Nic, Yes i tried to access same DB in 2 different formats {novice IMS guy ... i wouldnt get great ideas}

My DBA was suggesting me this ... "Since IMS database is hierarchical. It contains pointers in the segments. UACOTP is a HIDAM database which means it has a Hierarchical Index database (UACOTI) that points to the root-database (see attached). That why you have to use an unload-JCL to unload the segments using the old DBDLIB to a flat-file (without the pointers), then do the data-conversion, then re-load it to the new DBDLIB"

Will this work too? I have two files which i use in FAIMS, which one should i unload and can i use UNload/EXTRACT option of FAIMS?

Any sample jcls to do this will be helpful. Unfortunately my DBA or shop doesnt have one.

Since im very new to IMS .... looks like i will have a good time

Anuj Dhawan · Posted: Wed Sep 12, 2012 8:13 pm

Rakesha - you're mixing your concerns with good amount of local jargons. I'll assume by FA-IMS you mean "File-Aid for IMS". If yes, you can use "unload option" but then it'll give a format which File-Aid understand not the COBOL program which you've mentioned in first post of yours.

How do you make sure that before this

dick scherrer · Posted: Wed Sep 12, 2012 8:17 pm

Hello,

Not sure where you are wioth this, but one method that has worked on many, many database systems is to:

1. Backup the test database(s) to be changed.
2. Stop all use of the test databse(s).
3. Unload the data.
4. Modify the data per the 2 copybooks.
5. Remove the old "ddl" and catalog the new ddl.
6. Load the reformatted data.
7. Check for any problems.

When the procedure is validated in test, schedule when this can be done in Production. The testing should include full volume as you need to be able to predict how much time is needed for Production.

Nic Clouston · Posted: Wed Sep 12, 2012 9:04 pm

I let it slide re JCL etc but really just unload using your cobol program modified to only read and write to file and then another version modified to read the file and write to the new DB

dick scherrer · Posted: Wed Sep 12, 2012 9:10 pm

Hello,

Depending on the volume of data, reading/writing individual entries may require an unacceptable amount of time/resources.

don.leahy · Posted: Wed Sep 12, 2012 9:36 pm

And do remember to add some extra space in the VACODTA segment so that the next time you need to increase a field size (and there *will* be a next time) or add a new field, the conversion will be relatively painless.

rakesha.hg · Posted: Thu Sep 13, 2012 11:49 am

hi All,

Thanks for your time and replies.

I was able to Extract the data using "File aid - IMS option" and also i could do the same extract using a jcl with

Anuj Dhawan · Posted: Thu Sep 13, 2012 2:38 pm

rakesha.hg · Posted: Thu Sep 13, 2012 5:34 pm

Anuj,

rakesha.hg · Posted: Mon Sep 17, 2012 4:39 pm

hi All,

Just finished loading the DB with the Converted file.
One thing i observed was my converted record (275 length) had valid data till the last byte, but when i reloaded this file to IMS DB using my new expanded DBD - Data seems to fine for the first 255 bytes (which was the original length of unload) and starting 256 - 20 bytes of low values have been initialized

.

Looking at my DBD which has rule like