SET LOCK FILE UPDATE

[Pickering, John (NORBORD)]

Leonard

No locking will occur if there are no output statements. And with output
statements, only the file in output statement will be locked.

With "set lock file update" you will force Qtp to issue dblock/dbunlock
pairs around each dbput or dbupdate. This allows others to update the
database while the Qtp is executing but obviously there is a performance
penalty for the extra image calls (but who cares these days, hardware is
cheap :-) and there is the question of attempting to update a record in the
output phase which has been changed by some other process since the input
phase -- but only you know the app well enough to evaluate this risk.

Regards,
JWP

-----Original Message-----
From: Leonard_Berkowitz@harvardpilgrim.org
[mailto:Leonard_Berkowitz@harvardpilgrim.org]
Sent: Wednesday, January 15, 2003 12:10 PM
To: powerh-l@lists.swau.edu
Subject: SET LOCK FILE UPDATE


MPE/iX 6.5; PowerHouse 8.19C

>From the manual:

SET LOCK FILE

"Individual locks are applied for each dataset involved. Datasets not
mentioned are not locked."

UPDATE

"The SET LOCK UPDATE statement specifies that locking is applied only for
the duration of each individual update. Since the SET LOCK UPDATE statement
lets other users change the data betwen the time the data record is read
and the time it is updated by QTP...[checksum is used to compare the images
of the record in play]"

We have a program into which SET LOCK FILE UPDATE was added several months
after being installed into production, apparently (not sufficient
documentation in the program <sigh!>) to keep the environment stable for
the duration of the RUN. In fact, there is no UPDATE verb in the program at
all.

Here is the question: Is any entity, in fact, locked since no updating
occurs?

Thanks.
--
Leonard S. Berkowitz
Perot Health Care Systems