RE: SETOBJACC and file performance

["Forbes, Vincent" <Vincent.Forbes@xxxxxxxx>]

We do it here to help our batch times & there is a significant performance
improvement.

However, it's all or nothing.  You can also load logical files {if smaller}.


We added more ram to accommodate our 6 files.

\Vincent

 -----Original Message-----
From:   Tony Carolla [mailto:carolla@xxxxxxxxx] 
Sent:   December 8, 2004 3:51 PM
To:     RPG programming on the AS400 / iSeries
Subject:        Re: SETOBJACC and file performance

Hmmm... That sounds promising.  I wonder if the system makes a
judgement as to how much of the object to load.  Example, I have a
13.7Million record 1.4GB file, and I obviously wouldn't want to tie up
1.4GB of memory, but would the system manage placing only reasonable
portions thereof, based on the pool size?


On Wed, 8 Dec 2004 15:44:22 -0500, CWilt@xxxxxxxxxxxx
<CWilt@xxxxxxxxxxxx> wrote:
> Tony, it should certainly speed things up assuming it is used properly.
> 
> SETOBJACC "preloads" the object into physical memory.  If used to place
the
> object in an unused memory pool, the object will remain in that pool an
> never be swapped out to disk.  Once the object is completely loaded into
> memory, no physical disk I/O need be performed.
> 
> This would be particularly beneficial with RANDOM I/O to the object.  With
> sequential I/O, I believe you could use blocking to achieve about the same
> benefits.
> 
> Double check that the object is being placed into an unused pool however.
> If not, the it is likely that the object ends up being swapped out and you
> lose the benefits of SETOBJACC.
> 
> Charles Wilt
> iSeries Systems Administrator / Developer
> Mitsubishi Electric Automotive America
> ph: 513-573-4343
> fax: 513-398-1121
> 
> 
> 
> 
> > -----Original Message-----
> > From: Tony Carolla [mailto:carolla@xxxxxxxxx]
> > Sent: Wednesday, December 08, 2004 3:26 PM
> > To: RPG programming on the AS400 / iSeries
> > Subject: SETOBJACC and file performance
> >
> >
> > I am working with an application that maintains a copy of data from
> > several libraries, and uses a brute-force 'read all records and
> > compare' strategy.  Inside the CL that calls the RPG, the files that
> > are to be read from are specified in several SETOBJACC commands.  The
> > help for this command leads me to believe that this is set up to
> > accelerate the performance of database READs/WRITEs/UPDATEs.
> >
> > Does anybody have any experience with this method?  Does it simply
> > allow larger record block sizes?  What are the pitfalls, and finally,
> > if I am updating files that have dependent logicals, is this safe?
> >
> >
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