Re: Buffering

[Charles Wilt <charles.wilt@xxxxxxxxx>]

In answer to your question, yes RPG's buffering is prior to the record
being passed to the Db and thus prior to journal entries being created...

Also note that RPG won't buffer records output to a file with unique keys
(as the Db has to have them to enforce the uniqueness)

Is commitment control being used by chance?

Charles

On Thu, Nov 21, 2019 at 11:00 AM Craig Richards <craig@xxxxxxxxxxxxxxxx>
wrote:

> Hi All,
>
> I'm trying to track down an infrequent but troublesome bug.
>
> My best guess at the moment is that it is caused by an RPG program
> buffering output so that not all records have hit the disk when an
> asynchronous process wants to read them and run some SQL joins.
>
> However, looking at the journal receivers, according to the sequence
> numbers - the records are being written in the correct order.
>
> Apologies in advance if this is a stupid question but my assumption is that
> if an RPGLE program is buffering output, there won't be journal entries for
> writes to that file until the data is actually written to disk.
> But I'm not certain of this...
>
> Maybe an example would be clearer:
>
> Program A - Batch Server Process (stays resident)
> Writes Order Line.
> Writes Order Header.
> Sends Data Queue Entry to wake up Program B running in another Batch Server
> Process
>
> Program B - another Batch Server Process (stays resident)
> Requires the Order Header and the Order Line records in order for the SQL
> join to select some rows.
>
> Looking in the journals, I can see, in sequence number order:
> Program A Write to Order Line
> Program A Write to Order Header.
>
> Is this journal sequence conclusive proof that the Order Line was present
> on disk before the Order Header was?
>
> If Program A was buffering output, such that the Order Line records,
> written chronologically first, sat in Program A's buffer until some time
> after the Order Header records hit the disk - would the journal sequence
> numbers indicate that?
>
> Obviously I can use FEOD or Block(*No) in Program A for file Order Line but
> there is no point in doing that if the journal sequence numbers are already
> telling me that the records from the Order Line got there before the Order
> Header.
>
> thanks kindly,
> Craig Richards
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