Re: Externalizing Data Access - Reducing Disk I/O

Charles -

In my original debugging, it did not appear to be working. In reading
what you all are saying, I think I need to look again.

Thanks,
Brian

------------------

Note that you aren't really incurring extra disk I/O.

On the initial chain, the system must page the record in from disk.
As long as that page remains in memory, the system will not re-read it
from disk on subsequent chains. Actually, given the single level
store, the data doesn't theoretically exist on the disk for it to
read!

However, the record data is still copies from the DB page in memory to
the in memory buffers of the RPG program. So you can get a
performance boost by not chaining repeatedly; but not as big a boost
as you might expect. In fact, I seem to recall that in certain cases,
the system will skip the copy to the program buffer if the data hasn't
changed.

I'm a little confused by your statement, "My hope (and coding) was
that the subprocedure retained knowledge of existing record in memory,
and prevent the additional chain, but that doesn't appear to be the
case."

The code you posted seems to check if it's going to be chaining for
the same record, are you saying it's not working?

HTH,
Charles


This message and any attached documents contain information which may be confidential, legally protected or exempt from disclosure under applicable law. These materials are intended only for the use of the intended recipient. If you are not the intended recipient of this transmission you are hereby notified that any use, distribution, disclosure, printing, copying, storage, modification or the taking of any action in reliance upon this transmission is strictly prohibited. If you have received this communication in error, please immediately notify the sender and delete the message from your system and destroy any print-outs and copies. Polo Ralph Lauren reserves the right to record and monitor email communications through its networks for the purposes of eliminating potential viruses, blocking unsolicited emails, filtering out illegal or offensive content, and for investigating and detecting any unauthorized use of its systems as well as ensuring its effective operation. The content of this email is not legally binding unless explicitly confirmed by letter. Please note that it is your responsibility to scan this message for viruses.