Re: Expanding a field in a file or adding a new field to the file -- MIDRANGE-L

This is the option I'd go with...

Specifically,
Create the new table with the new longer field
Create a logical (or view) with the name of the original table/PF and the
just original set of columns.
Modify all existing logicals & views to point to the new table with just
the original set of columns.

Done properly, you don't have to recompile _any_ programs.
(RPG programs using native I/O on Indexes are problematic, as while you can
create an index with a subset of included columns, the DB will put the
index columns first in the record layout. So you may need to recompile
those. )

Create a new view (or index or logical) that explicitly includes all the
existing columns.
Now modify all of the programs that actually need access to the token to
use the new view.

Lastly decide if you want to simply blank out the original token field, or
store some some substring of the new token in it. If the latter, I'd add a
before insert/update on change of NEWTOKEN trigger to the table to maintain
the old column.

Going forward, make sure you don't have any RPG program using native I/O to
the actual table, they should always be accessing the data through an
view/logical/index with an explicitly set of included columns. Now you can
add columns to your hearts content without recompiling the world.

Char;es

On Wed, Jul 31, 2019 at 8:02 AM Justin Taylor <JUSTIN@xxxxxxxxxxxxx> wrote:

I don't personally like option 2 in general.

If option 1 is too much work to accomplish for one massive deploy, how
about this strategy?
Create a new table (different name) that matches the layout of the
original except the column in question will be longer. Create a LF over
the new table with the matching layout, except the column in question has
the original length. Load the new table with the original data, and then
replace the old table with the new LF (rename LF to be old table name).
Existing programs have the layout they expect and you have more time to
migrate to the longer column.

-----Original Message-----
From: Alan Shore via MIDRANGE-L [mailto:midrange-l@xxxxxxxxxxxxxxxxxx]
Sent: Wednesday, July 31, 2019 8:03 AM
To: midrange-l@xxxxxxxxxxxxxxxxxx
Cc: Alan Shore <ashore@xxxxxxxx>
Subject: Expanding a field in a file or adding a new field to the file

Hi everyone
Before I forget - we are on V7r3
Are we all sitting comfortably - then let me begin

We presently hold tokens instead of credit card numbers and the web
service calls that are made for settling, authorization, refunds etc. use
the token The token was of a length that we could store it in the old
credit card number field - 17 characters However - we have been informed
that the size of the token is going to increase - to larger than 17
characters

I understand that there will be NUMEROUS service programs, files, programs
etc, that will need to be changed and tested

Here is my question -
Opinion based or fact based - What would be better -

1. expanding the present field from 17 to a much larger field (say
50 - just in case of future increases)

2. Adding a new field (at the end of all the files)

Each has their own foibles (for want of a better word) For example:-

Option 1 - EVERY program that even touches any of the files that this type
of file change is applied to will need to be re-compiled (minimum) - even
if the program has nothing directly to do with this expanded field. However
it will be the same field name, therefore only need to be concerned about
the new field size and what is happening to that field (populating another
field for example)

Option 2 - EVERY program, service program etc. will need to be changed to
use the new field name. Not only need to be concerned about replacing the
old field name with the new field name within the program, service program
etc. but also need to be concerned about the new field size and what is
happening to that field (populating another field for example)

If anyone has more options - please feel free to pass those on

As always - all answers gratefully accepted

Alan Shore
E-mail : ASHORE@xxxxxxxx
Phone [O] : (631) 200-5019
Phone [C] : (631) 880-8640
'If you're going through hell, keep going.'
Winston Churchill

--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: https://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxxxxxxxx
Before posting, please take a moment to review the archives
at https://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: https://amazon.midrange.com