RE: Converting large amount of data

["Therrien, Paul" <ptherrien@xxxxxxxxxxx>]

You would think there would be a large note after this paragraph to emphasize that these rules do not apply if the recode formats are different.
I had to read the paragraph twice to see the " ... physical and logical files that share the same record format:"

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxxxxxxxx] On Behalf Of Joe Pluta
Sent: Thursday, January 28, 2021 4:05 PM
To: midrange-l@xxxxxxxxxxxxxxxxxx
Subject: 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
> --
> IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600 Mail
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>            Ft. Wayne, IN 46818
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>
> -----Original Message-----
> From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of
> 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.