Re: Speed in Reading -- RPG400-L

Sent that too fast...

In other words, if the pool is being used to run jobs, the only way
"repeated use" of SETOBJACC would help would be to continuously issue
the SETOBJACC with nothing done in between.

loop:
SETOBJACC OBJ(MYPF) POOL(*BASE)
GOTO LOOP

If then pool isn't being used to run jobs, then you only need to use
SETOBJACC once.

HTH,
Charles

On Mon, Jun 7, 2010 at 4:33 PM, Charles Wilt <charles.wilt@xxxxxxxxx> wrote:

The problem with your understanding is that if the pool is being used
to run jobs, then as soon as the SETOBJACC completes, all or part of
the object may be paged out. In fact, I believe that parts of the
object paged in could already have been paged out again before the
SETOBJACC command even completes!

If the pool isn't being used to run jobs, then then an object placed
into memory by SETOBJACC will remain there till IPL or SETOBJACC
*PURGE is used.

HTH,
Charles

On Mon, Jun 7, 2010 at 4:10 PM, Peter Connell
<Peter.Connell@xxxxxxxxxxxxxxxxx> wrote:

To me the help text implies that use of the command triggers an event which brings the object(s) into memory in whatever pool is referenced and that repeated use would negate any possibility that the OS may have paged it out irrespective of other activity in the pool.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Charles Wilt
Sent: Tuesday, 8 June 2010 8:04 a.m.
To: RPG programming on the IBM i / System i
Subject: Re: Speed in Reading

I believe you're reading the help wrong...

If you're talking about this blurb:
"Repeated use of the command can cause a set of objects to be resident
in a main storage pool."

All it is saying is that you can do
SETOBJACC OBJ(PF1) POOL(*SHRPOOL10)
SETOBJACC OBJ(PF2) POOL(*SHRPOOL10)
SETOBJACC OBJ(PF3) POOL(*SHRPOOL10)
SETOBJACC OBJ(PF4) POOL(*SHRPOOL10)

To bring a set of objects into memory.

The only way to ensure an object remains in memory is to put it into a
pool that is not running jobs.

HTH,
Charles

On Mon, Jun 7, 2010 at 3:53 PM, Peter Connell
<Peter.Connell@xxxxxxxxxxxxxxxxx> wrote:

Note that the help panel for the SETOBJACC command also suggests that repeated use of the command should ensure that the objects remain resident.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Bryce Martin
Sent: Tuesday, 8 June 2010 7:35 a.m.
To: RPG programming on the IBM i / System i
Subject: Re: Speed in Reading

Thanks Vern. That definitely makes more sense.

Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777

Vern Hamberg <vhamberg@xxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
06/07/2010 01:52 PM
Please respond to
RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>

To
RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>
cc

Subject
Re: Speed in Reading

As Charles said, you don't run SETOBJACC in an application program -
it's a one-time thing best done at IPL. Once something is in memory, it
is available to all jobs on the system, no matter the pool THEY are
running in.

The pool for putting data resources into with SETOBJACC is, if I
remember, best set up as a fixed-size, private pool (not shared) with
absolutely no jobs running in it - those would have the potential of
paging stuff out.

HTH
Vern

On 6/7/2010 7:29 AM, Bryce Martin wrote:

Thanks for the link Kurt. Learn something new everyday.

So I'm guessing that the file gets loaded into the pool at application
startup the first time it is run.... anybody know if that significantly
impacts the program's load time? I would think those, but that you

should

gain that back during the processing.

Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777

Kurt Anderson<kurt.anderson@xxxxxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
06/04/2010 05:09 PM
Please respond to
RPG programming on the IBM i / System i<rpg400-l@xxxxxxxxxxxx>

To
"'RPG programming on the IBM i / System i'"<rpg400-l@xxxxxxxxxxxx>
cc

Subject
RE: Speed in Reading

Whoops, meant to include a couple links in my response.

For Bryce, SETOBJACC:

http://www-01.ibm.com/support/docview.wss?uid=nas1dc0a2297bdaefddb86256d6c0069907f

And the document I'm looking at in regard to OVRDBF SEQONLY (which

likely

has the answer to my questions, but I may not be reading it right).

https://www-912.ibm.com/s_dir/slkbase.NSF/1ac66549a21402188625680b0002037e/d6738e1cd37e1f33862565c2007cef79?OpenDocument

-Kurt

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx

[mailto:rpg400-l-bounces@xxxxxxxxxxxx]

On Behalf Of Charles Wilt
Sent: Friday, June 04, 2010 3:46 PM
To: RPG programming on the IBM i / System i
Subject: Re: Speed in Reading

Not quite right...

It doesn't matter if you use SQL or RPG RLA to read or write the file.

What matters is if you use SQL DDL or DDS to create the file in the

first

place.

HTH,
Charles

On Fri, Jun 4, 2010 at 4:26 PM, Luis Rodriguez<luisro58@xxxxxxxxx>

wrote:

You are right, SQL checks during Writes, RPG native I/O checks during

reads.

I like to refer people to this nice Dan Cruikshank paper: "Modernizing
Database Access The Madness Behind the Methods ",. You can find it at:

http://www-03.ibm.com/systems/resources/systems_i_software_db2_pdf_Performance_DDS_SQL.pdf

HTH,

Luis Rodriguez
IBM Certified Systems Expert - eServer i5 iSeries

On Fri, Jun 4, 2010 at 3:31 PM, Bryce Martin<BMartin@xxxxxxxxxxxx>

wrote:

I'm not sure what SETOBJACC is or what effect it has on reading a

file...

but....

Doesn't RPGLE do its checks on Read as opposed to SQL that does checks

on

Write? So as I've heard it the general idea goes that reading with

SQL

should be faster than RPGLE but writing would be the other way around.

So

why not write and SQL to read the data and only the fields you need

(which

is proven to be faster than specifying SELECT * FROM)? You can fetch

more

than one row at a time I do believe and I think would perform better

than

a single record by record read using native I/O.

Then again, if I have the idea of when the i/o checks happen

respective

to

read vs. write then everything I said above is for naught!

Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777

Kurt Anderson<kurt.anderson@xxxxxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
06/04/2010 02:12 PM
Please respond to
RPG programming on the IBM i / System i<rpg400-l@xxxxxxxxxxxx>

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"'RPG programming on the IBM i / System i'"<rpg400-l@xxxxxxxxxxxx>
cc

Subject
Speed in Reading

Hi all,

Lately I've been dealing with a new client that has a high volume of

data

for us to process, so I've been looking at various ways to get things
moving a little faster.

I believe I've successfully implemented the use of SETOBJACC with the

help

of Chuck Pence& Mark Waterbury (thanks guys).

Now, this may be grasping at straws, but in a high data volume

situation,

should I see any benefit in restricting the fields in a LF to only the
fields used by the program? (In essence, going from record length of

438

to 138.) My brain says, "yes," but the logic under-the-covers may not
match the logic my brain uses to come to its conclusion.

I'm also curious about RPG blocking. This question mainly goes out to
people using file encapsulation service programs, but is obviously

open

to

anyone to answer. I have a file wrapped up in a service program. This
service program pretty much handles all I/O operations for the file.

Now,

if all I want to do is loop through the file, it's not going to block

read

because it has operations such as READE in the service program. I

wish

block-reading would be determined at run-time (again, a wish without a
full understanding of the compiler does its thing). I'm curious how
people have circumvented this limitation?

Thanks,
Kurt Anderson
Sr. Programmer/Analyst
CustomCall Data Systems
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