Rewrite on GDG generation.

che · New User Joined: 31 Mar 2005 Posts: 6 Location: Chennai

Problem goes like this.

Is it possible to rewrite or update on a current generation of a GDG base.

If so could anyone say how i access my current generation to write a set of records and update records which are already there.

My run JCL would creates a GDG generation for every new write from a program.

Thanks in advance to fellow forum mates.

priyesh.agrawal · Posted: Fri Jul 22, 2005 3:27 pm

HI che,

che · New User Joined: 31 Mar 2005 Posts: 6 Location: Chennai

how to access the current generation (write fail generation of prev time) from the program.

what mode do i open the file (i,O,IO,extend) and do i use write or rewrite .....????

Thanks for a quick reply priyesh.

Thanks for all other forum mates for having a look.

priyesh.agrawal · Posted: Fri Jul 22, 2005 4:41 pm

Hi che,

che · New User Joined: 31 Mar 2005 Posts: 6 Location: Chennai

Dude

I do know every generation is like a flat file and you could use it as like a flat file.Guess u didn't get what i said.

lemme say it once again and u try helpin me..

say i have some data(say 3 records) in my GDGFILAV008...while writing 4th record write fails.

i restart my program which selects records from (say 4th record) onwards.
i need to write the selected records to an existing GDGFILAV008 generation. this is an update on an existing file.

if i run my RUNJCL data which is fetched on by select ?ery wud be written on to a newer generation say GDGFILAV009.

i don't want this.also if there are any half written records(say record 4)..it should be updated.i also need the existing records.

Let me know if one of you could help me in this.

priyesh.agrawal · Posted: Fri Jul 22, 2005 6:35 pm

Hi che....

You have 3 records in latest generation of the GDG and in the program you want to append the records from 4th onwards to the latest generation.

So you have to open your GDG Gen in prog as Extended mode....

rssomm · New User Joined: 05 Jun 2005 Posts: 41 Location: Hyderabad

Hi Che....

For a GDG, you can have upto 255 generations and 100(0 to 99) versions.

For example if u have generation TEST.GDG(0) [TEST.GDG.G001V00], which you wanted to update due to some reason you can use following technique.

Use Input file as TEST.GDG.G001V00 and output file as TEST.GDG.G001V01.

When u refer this Generatin later as TEST.GDG(0), It always refers latest version, say in this case TEST.GDG.G001V01.

If u want to refer previous version for any reason you can always refer as TEST.GDG.G001V00.

As far as my knowledge, this is the only way u can solve your prob .

Thank U.
Madhu

anuradha · Posted: Fri Jul 22, 2005 9:11 pm

Hi Che!

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

Hey Dude,

1) You can only update DISK flat files.
2) Both TAPE and DISK flat files can be extended.
3) You open the file as I-O to update and/or extend.
4) To extend only you can use extend open option.
5) Use DISP=OLD in the JCL, the open will give you MOD if you need it.
6) In JCL you can ref the file relatively (DSN=....(0)) or absolutely
(DSN=.....GnnnV00)

shobam · New User Joined: 18 Jul 2005 Posts: 34 Location: CN

If there is a failure in the program while it is writing the 4th record , while restarting the job try overriding the DSN parameter from GDG(+1) to GDG(0) and also change the DISP parameter from OLD to MOD.

Since you are going to ADD and also UPDATE a record in the GDG , open the file in I-O mode.

Please correct me if I am wrong.