Re: File that has records constantly being added and deleted

At 07:13 AM 9/26/2006, you wrote:

A word of warning about using a data queue. Space management on data queues is very poor in OS/400. If you add records to a data queue and for any reason, the

program that removes records from the data queue is not running, then the data

queue will expand to contain the buildup of records. However, contrary to what

you might expect, the size of the data queue never goes back down once the

records are removed. At that point, you're stuck with a rather large data queue

space and, as far as I've been able to see, the only recovery is to delete the
data queue and then rebuild it from scratch.

Rich Loeber
Kisco Information Systems
http://www.kisco.com
  ------------------------------------------------------------------------

Don Tully Sr wrote:

> There is absolutely no down side to reuse deleted records.  The performance

> issues are very close to zero. All applications that I have written for the

> past 13 years have all files set to reuse deleted records.  It certainly
> eliminates the downtime problems associated with file reorgs.
>

> If you must guarantee that records are processed in write sequence, then you

> must add a key, perhaps timestamp.  Obviously the relative record number
> will no longer indicate the sequence the records were written to the file.
>
> If you want to go to the effort of using a data queue, that certainly could
> also be a way to go.  I have also written many data queue routines for high
> performance requirements.
>
> Don Tully
> Tully Consulting LLC
>
> -----Original Message-----
> From: midrange-l-bounces@xxxxxxxxxxxx
> [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of James H H Lampert
> Sent: Monday, September 25, 2006 5:24 PM
> To: midrange-l@xxxxxxxxxxxx
> Subject: File that has records constantly being added and deleted
>
> Here's the situation:
>
> We have a file. Any arbitrary number of jobs can put
> records into the file; a single dedicated job reads the
> records, in arrival sequence, processes them, and deletes
> them. We thus have a file that rarely has more than a few
> active records, but accumulates lots and lots of deleted
> ones.
>
> Is there a way to squeeze out deleted records without
> having to grab an exclusive lock on the file? Or would it
> be more sensible to set it to re-use deleted records, and
> modify the processing program to read by key? Or are there
> other ideas?
>
> --
> JHHL
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