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  3. May 2012

Re: committment control and file changes

Why not just prove it in reality for them, write a simple program that
uses an LF to read/write/update then rollback the changes. After the
rollback let them query until their fingers bleed trying to find the
records they just *know* weren't rolled back. Like Alan alluded to they
most likely are still in the program in debug and check the variable
values, not the actual record itself.





From: Alan Campin <alan0307d@xxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>,
Date: 05/30/2012 05:50 PM
Subject: Re: committment control and file changes
Sent by: midrange-l-bounces@xxxxxxxxxxxx



Record not re-read after the change rolled back?

On Wed, May 30, 2012 at 4:49 PM, Stone, Joel <Joel.Stone@xxxxxxxxxx>
wrote:
I agree, but I am arguing with other pgmrs here who swear that chgs to
LF's don't roll back, but chgs to the based-on PF will roll back.

I would like someone on this BBS to explain how that is possible??



-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Alan Campin
Sent: Wednesday, May 30, 2012 5:25 PM
To: Midrange Systems Technical Discussion
Subject: Re: committment control and file changes

If a logical is just a SQL View and an SQL Index in one object and the
physical file it is based on is rolled back, why wouldn't the view and
index over the physical have the same values? It is just a projection
of the physical file.

On Wed, May 30, 2012 at 4:14 PM, Stone, Joel <Joel.Stone@xxxxxxxxxx>
wrote:
Yes, but...

If a PF is journaled, will a record update to a LF (based on that PF)
roll back under CM in the same manner that an update to the PF would?

Thanks for response!

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Vern Hamberg
Sent: Wednesday, May 30, 2012 5:00 PM
To: Midrange Systems Technical Discussion
Subject: Re: committment control and file changes

Joel

Have you looked at the help text of STRCMTCTL? It mentions some
requirements - among them, the file which will be processed under
commitment control must be journaled. There is NO journaling of LFs -
or
of OPNQRYF or anything other than PFs, as far as files go.

OPNQRYF is not a real file - it is a virtual access path, one could say
- no data contained therein, only a PATH to the data, known as an ODP
or
open data path.

Likewise, LFs are only an access path.

You should also look at the STRJRNPF command - more information there.

You should also look at the COBOL reference to see how to specify using
commitment control on a file - in RPG it is on an F-spec - I don't know
the equivalent.

It's all in the manuals at Infocenter - this is a pretty big topic,
much
going on around what might seem a simple question!!

HTH
Vern

On 5/30/2012 3:16 PM, Stone, Joel wrote:
Physical file changes under commitment control can be rolled back for
errors.

Do Logical files behave the same way ie the underlying PF would roll
back the same way that direct PF updates would? Or are there some
restrictions on LF's that would cause programmers to use the LF to read
the PF by primary key and update the PF directly?

Do OPNQRYF's behave the same way as PF's also? Ie will the based-on
PF roll back on an error while under commitment control?

Does the file output method matter? Ie if a file is opened as OUTPUT
vs UPDATE would both of these behave the same ? ie rollback on error
under CC?

Some pgmrs here claim that PF updates roll back nicely, whereas LF
updates do NOT roll back. Is this possible? (assuming all files are
journalled properly and such)

Thanks!





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