AW: Stored Procedures vs. SQL Statements vs. CHAIN

Hi,

I don't think that using stored procedures instead of embedding the SQL
statements directly will be a big advantage, in contrary.

Stored procedures are ideal for client server applications to group SQL
statements together and minimize data transfer between client and server.

A stored procedure is nothing else than a program that can be called from
any SQL interface. In this way when calling a stored procedure a dynamic
program call will be executed, with all its overhead.

In my opinion grouping the SQL-statements in RPG-procedures in
Service-Programs with named activation groups will be the best solution. 

For each SQL statement the optimization-szenario gets executed, that means:
- Access plans get built or validated
- Indexes get checked
- Open data paths get created 

If you code 3 time the same SQL statement in the same program the
optimization get executed three times and three different OPDs will be
built. 

If you put the same statement into a RPG-procedure in a service programm
with a named activation group. The optimization is only executed once per
job and the ODP can be reused, when ever you call this procedure.
(assumed the ODP is reuseable). 

Birgitta

"If you think education is expensive, try ignorance"
(Derek Bok)
 

-----Ursprüngliche Nachricht-----
Von: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von Vernon Hamberg
Gesendet: Freitag, 5. Mai 2006 14:50
An: Midrange Systems Technical Discussion
Betreff: RE: Stored Procedures vs. SQL Statements vs. CHAIN

To make things murkier - a stored procedure on iSeries can be a call 
to a regular program - this is an external procedure, IIRC. And that 
program can do whatever - native IO, anything they do now. You can 
even call QCMDEXC using the SQL CALL statement that is used to call 
an SP. Or a stored procedure could be almost the same, if defined as 
an SQL-type procedure, from the embedded stuff you have now - 
assuming you are using embedded and not RUNSQLSTM or QMQRY.

I think there will be little advantage to going with a stored 
procedure over embedded methods - and you add some complexity in 
development and maintenance of the application that might not justify 
the change. But if you can experiment, fun some benchmarks and let us 
know - good stuff.

Later
Vern

At 07:42 AM 5/5/2006, you wrote:

>Thanks for the great info, Charles.
>
>I've run all of my statements through the query advisor and set up the
>appropriate indexes (when it has advised I should set up an index).
>However, I'd like to optimize it if I can a bit further, so I thought
>I'd travel the stored procedure route to see if it would make a
>difference.
>
>I think a huge issue right now is our box.  We're hitting well over
>double in out interactive sessions at peak times, so the box is doing an
>awful lot of thrashing.  I'm hoping that the new box will eliminate this
>issue.
>
>Brian.
>
>-----Original Message-----
>From: Wilt, Charles [mailto:CWilt@xxxxxxxxxxxx]
>Sent: Friday, May 05, 2006 8:33 AM
>To: Midrange Systems Technical Discussion
>Subject: RE: Stored Procedures vs. SQL Statements vs. CHAIN
>
>Brian,
>
>Generally speaking, an SQL statement that updates "several hundred"
>records in one shot would be faster than updating the same records using
>native I/O.
>
>IIRC, SQL is generally faster for updating when you get above 100
>records.
>
>However, you're dealing with a "series of SQL statements".
>
>If you'd have to replace the series of SQL statements with a series of
>native I/O statements, then I'd say stick with the SQL.
>
>If you could replace the series of SQL statements with a single set of
>native I/O, you could possibly find the native I/O to be faster.
>
>On the other hand, if you can use a single set of native I/O statements,
>you should also be able to use a single SQL statement.  Going back to
>the first sentence, the single SQL statement would be your fastest
>method.
>
>
>Are you not happy with the performance as it stands now?
>
>Have you made sure that the appropriate indexes are in place?
>
>HTH,
>
>Charles Wilt
>--
>iSeries Systems Administrator / Developer
>Mitsubishi Electric Automotive America
>ph: 513-573-4343
>fax: 513-398-1121
>
>
> > -----Original Message-----
> > From: midrange-l-bounces@xxxxxxxxxxxx
> > [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Brian Piotrowski
> > Sent: Friday, May 05, 2006 8:17 AM
> > To: Midrange Systems Technical Discussion
> > Subject: Stored Procedures vs. SQL Statements vs. CHAIN
> >
> > Hi All,
> >
> >
> >
> > Can someone tell me in terms of speed which method would be best when
> > working with multiple records?  Right now my code uses a series of SQL
> > statements to update several hundred records in one shot.
> > I'm thinking
> > about moving these statements to a stored procedure instead, but I
> > wanted to weigh my choices against a good old CHAIN command as well.
> >
> >
> >
> > Anyone have any thoughts or comments?
> >
> >
> >
> > Also, can someone please recommend a good Redbook that
> > discusses Stored
> > Procedures on the i5?
> >
> >
> >
> > Thanks!
> >
> >
> >
> > Brian.
> >
> >
> >
> > -=-=-=-=-=-=-=-=-=-=-=-=-=-
> >
> > Brian Piotrowski
> >
> > Specialist - I.T.
> >
> > Simcoe Parts Service, Inc.
> >
> > PH: 705-435-7814
> >
> > FX: 705-435-6746
> >
> > -=-=-=-=-=-=-=-=-=-=-=-=-=-
> >
> >
> >
> > --
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