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On 24/10/2006, at 1:49 PM, Pete Helgren wrote:
Where am I missing the boat? I thought the OVRDBF would allow the file to be read and updated by both programs. Am I wrong about that?
Yes, you're wrong. The file can be read and updated by multiple jobs but only one job can actually update a particular record at a time. The job that currently holds a record lock on the record can update it. Any other job attempting to read the record for update will get wait for the job default wait time (usually 30 seconds) and will then get an I/O error because the record is not available.
midrange.com
Both the posting program and the maintenance program should either:
a) Catch the I/O error and inform the user who holds the lock
or
b) Read with no lock until an update is about to be performed and then
re-read the record with a lock and make the update.
Option a) is the easiest because b) needs to do it also (in case the record is already locked on the second read) and it needs to handle the case where the record was changed by another job between the time it was displayed to the user and the time the attempt the update.
This has been discussed in the archives countless times. You'll find discussions on how to handle all scenarios and the IBM documentation has similar information. (Data management Guide I think.)
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