Re: Embedded SQL - performance question

Depends on your idea of sense :)

If you normally expect the record not to be there...
monitor;
write;
on-error DUPLICATE_KEY;
chain;
update;
on-error;
<other error>
endmon;

Is best from a performance standpoint...

The problem with this code
chain;
if %found;
update;
else;
write;
endif;

Is that the chain and the write are not atomic....you leave yourself
open to the record being added by some other process between the chain
and the write...what you'd really need would be

chain;
if %found;
update;
else;
monitor;
write;
on-error DUPLICATE_KEY;
chain;
update;
on-error;
<other error>
endmon;


Charles
endif;


On Fri, May 27, 2011 at 10:04 AM, Schutte, Michael D
<Michael_Schutte@xxxxxxxxxxxx> wrote:

Yes this is odd.

I don't like it myself.

Would have made more since to chain, update when found, insert when not found.

JMO

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Elbert Cook
Sent: Thursday, May 26, 2011 5:47 PM
To: 'RPG programming on the IBM i / System i'
Subject: RE: Embedded SQL - performance question

Sorry off topic.

I saw this piece of code on our system yesterday. I'm still not sure what to
think.

Exec Sql Insert Into myLib/myFile (Pattern, Color, Onhand) VALUES(:Pattern1,
:Color1, :Qty1);

IF SQLCOD = -803;
  Chain (Pattern1: Color1) myFile;
  IF %found;
     Onhand = Qty1;
     Update myFilef %fields(Onhand);
  Endif;
Endif;


-----Original Message-----
From: Joe Pluta [mailto:joepluta@xxxxxxxxxxxxxxxxx]
Sent: Thursday, May 26, 2011 5:13 PM
To: RPG programming on the IBM i / System i
Subject: Re: Embedded SQL - performance question

On 5/26/2011 3:16 PM, CRPence wrote:

    I expect that SQL should be much faster even on a poorly performing
system; almost as fast as the RLA, esp. if the same index is utilized
for both the SQL and RLA.

I've never found a single-record fetch to be anywhere near as fast as
RLA, and I did exhaustive tests; SQL doesn't catch up until the block
size is upped to about 100 records.  I could rerun all those tests, but
until someone shows me some evidence SQL has caught up, I have no reason
to repudiate the old data.

Joe
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