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  1.  Home
  2. RPG400-L
  3. January 2021

Re: clearing file currently opened in exit pgm

ACID properties guarantee data integrity in transaction-oriented database
systems, meaning record locking conflicts, duplicate keys, hardware
failures, and power loss will not corrupt the database. Commitment control
and pessimistic record locking are the HLL/OS features that enable ACID.
In the transaction environment, consistency is valued over availability.

The generally-accepted definition in the world of database is this:

- Atomicity (the entire transaction succeeds or fails--part of what
commitment control does)
- Consistency (a transaction will move the database from one state to
another correctly every time, meaning the data follows the appropriate
rules)
- Isolation (one transaction won't affect another transaction--another
part of commitment control)
- Durability (once a transaction is made permanent, it remains
permanent--the final stage of commitment control).

Why is this arcane knowledge significant? Because distributed databases
(especially in the cloud environment, where multiple copies of data improve
performance and replace backups) introduce a new set of headaches. Cloud
technology is pretty doggone cool (but I still bleed little i's).

Distributed database systems with BASE characteristics instead of ACID
(seriously, you can't make this stuff up) value availability over
consistency.

On Tue, Jan 19, 2021 at 4:22 AM Jay Vaughn <jeffersonvaughn@xxxxxxxxx>
wrote:

So I came to terms with the fact that I could not do the ftruncate64()
with a proceeding write to the file under the scenario of an exit pgm call.
I refactored my steps and approach and got an acceptable (if not better)
solution to my problem.

ACID = old school acronym for CRUD

Add
Change
Inquire
Delete

Jay


On Jan 18, 2021, at 1:45 PM, Reeve <rfritchman@xxxxxxxxx> wrote:

:) Didn't say you didn't, merely offering a suggestion. The behavior
you're
experiencing looks like a rollback has taken place.

COMMIT is a job/activation group function used to signal a transaction
made
up of multiple CRUD operations is complete. It's not issued against a
file: the idea of COMMIT is to maintain the integrity of the transaction
across multiple resources. Extra credit if you know the meaning of
"ACID"!

Use COMMIT/COMMIT WITH HOLD (if SQL) in your program and the changes to
the
resources opened under commitment control will be made permanent.

Just saying.


On Mon, Jan 18, 2021 at 4:56 AM Jay Vaughn <jeffersonvaughn@xxxxxxxxx>
wrote:

I know how to do commitment control in rpg for PF’s (both native and
sql)...

But what is the rpg syntax to issue a commit on a stmf?

Jay


Sent from my iPhone

On Jan 17, 2021, at 11:51 PM, x y <xy6581@xxxxxxxxx> wrote:

if the file is journaled, you'll need to do a COMMIT.

On Sun, Jan 17, 2021 at 4:43 PM Jay Vaughn <jeffersonvaughn@xxxxxxxxx

wrote:

So I have a stmf file opened in my exit pgm registered to
QIBM_QP0L_SCAN_OPEN.
I want to clear that file... and then later write to it further in the
exit
pgm.
I do a ftruncate64() in my exit pgm and if I do a wrklnk and look at
the
bytes, it did clear it and set the bytes to 0.
Good...
But when I later write to the file later on in the exit pgm, the data
I
thought I cleared returns and my new data appends to it.

Is this because the file was never closed before the new data was
written
to it?
How can I ensure it is cleared and then allowed to write to in this
same
exit pgm without the ability to close it before the write?

Is there some functionality with the below exit pgmoutput ds fields
that
can be set to allow my clear to "stick"?

8 8 CHAR(1) Update object scan information
9 9 CHAR(1) Scan status


tia

Jay
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