Re[2]: Dynamic arrays

[eric.delong@xxxxxxxxxxxxxxxxx]

     I haven't done any benchmarking in this, but personally, I rather 
     doubt that file I/O is going to outperform an array unless you're 
     talking about a very, very large array. The AS400 does a wonderful 
     job of caching dasd, but there is still a LOT of code that has to 
     be run to support file I/O. Is requested record in cache? If not, 
     gotta find the object, lock it, retrieve it. Any lock conflict 
     issues to resolve? Any field values that must be translated before 
     loading the buffer? (ie, date, timestamps, etc) Seems to me, 
     especially with RISC in the box, an optimized memory intensive 
     function like array lookup has a MUCH easier time just blasting 
     through an address space.......
     
     JMO,
     eric.delong@pmsi-services.com


______________________________ Reply Separator _________________________________
Subject: Re: Dynamic arrays 
Author:  <MIDRANGE-L@midrange.com > at INET_WACO
Date:    4/30/99 10:55 AM




Larry Bolhuis wrote:

> I haven't tested this but would not the use of SETOBJACC to move the
> file entirely into main storage give you almost the same speed boost
> with *ZERO programming?

Yes, SETOBJACC would likely be a much better performer than an array.   And with
50
records the amount of memory you'd have to count out would be negligible.  I 
believe
that the minimum that you could carve out for a subsysstem is 32K... more than 
enough
for this file.

But it may not even be worth doing at all because the AS/400 does such a darn 
good job
of memory management.  It naturally will keep frequently used data in main 
storage
anyway, and again, with such a small file it is very likely that the entire file
will
remain in main storage for the duration of the program anyway.

It would be interesting to bench mark, but I would suspect that your array 
program
would perform significantly worse than the program that just let Data Management
handle things.

jte

>
>
>  - Larry
>
> lg - Loyd Goodbar wrote:
> >
> > I have a work file (about 50 records) that is accessed very often by a RPG4
> > program. I was thinking about reading the file into an array to make lookups
> > faster. The problem is the file changes in size; sometimes it's 50 records,
> > sometimes 60, or 40, etc. I'd like to create a dynamically-sized array at
> > runtime. I briefly looked at the ALLOC/DEALLOC/REALLOC opcodes, but they
> > really didn't make much sense.
> >
> > Is there a relatively easy way of creating dynamic arrays in RPG, or am I
> > forced to create an arbitrary upper limit?
> >
> > Thanks,
> > Loyd
> >
> > --
> > "If we wanted more leisure, we'd invent machines
> >  that do things less efficiently." --Calvin & Hobbes
> > lgoodbar@watervalley.net  ICQ#504581  
http://www.watervalley.net/users/lgoodbar/
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> --
> Larry Bolhuis         | What do you want to reload today?
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