Re: Converting large amount of data

As others have mentioned, this actually is documented; it's in the DB2 bible, DB2 Universal Database for iSeries Database Programming.  It's not easy to find these days, here's an older copy:

http://ftpmirror.your.org/pub/misc/ftp.software.ibm.com/systems/power/docs/systemi/v5r2/de_DE/rbafomst.pdf

Here's the relevant text:

Record format relationships between physical and logical database files
When you change, add, and delete fields with the Change Physical File (CHGPF) command, the following relationships exist between the physical and logical files that share the same record format:
* When you change the length of a field in a physical file, you will also change the length of the logical file’s field.
* When you add a field to the physical file, the field is also added to the logical file.
* When you delete a field in the physical file, the field will be deleted from the logical file unless there isanother dependency in the DDS, such as a keyed field or a select or omit statement.

My takeaway on this is that CHGPF normally doesn't change logicals UNLESS the record format name is the same.  I can see why that would be, YMMV.


On 1/28/2021 10:15 AM, smith5646midrange@xxxxxxxxx wrote:

I just recreated his example on our V7.3 machine and the problem still
exists. Not even a report of any type to tell you that you might have a
problem with the second logical.

What a potential disaster waiting to happen!!!!!

-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Rob
Berendt
Sent: Thursday, January 28, 2021 10:39 AM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Subject: RE: Converting large amount of data

If you do need to do some digging I'm pretty sure the guy who wrote that
article would not be using any of those display to an outfile commands
unless he just had to. He is on the sql services bandwagon big time.

Rob Berendt
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Ft. Wayne, IN 46818
Ship to: 7310 Innovation Blvd, Dock 9C
Ft. Wayne, IN 46818
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smith5646midrange@xxxxxxxxx
Sent: Thursday, January 28, 2021 10:24 AM
To: 'Midrange Systems Technical Discussion' <midrange-l@xxxxxxxxxxxxxxxxxx>
Subject: RE: Converting large amount of data

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So in our conversion meeting yesterday, the CHGPF was discussed. Later
someone forwarded and OLD article to me from 2013 about a problem with CHGPF
relating to PF and LF record formats not matching (link below). At the
bottom of the article, it says the article was written for V7.1. We are
running on V7.3. Does anyone know if this is still an issue or do I need to
do some digging to find out if any record formats do no match?

https://www.rpgpgm.com/2013/06/chgpf-theres-quirk-that-can-bite-your.html#:~
:text=The%20Change%20Physical%20File%20(CHGPF)%20is%20a%20useful,the%20follo
wing:%20Delete%20all%20the%20dependent%20logical%20files.