RE: Memory Allocation Question

After about 1,000 to 10,000 records, you're better off using a User Index
for the best performance. There is not practical limit to the number of
entries.
-Bob


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Tony Carolla
Sent: Tuesday, November 09, 2004 2:52 PM
To: RPG programming on the AS400 / iSeries
Subject: Memory Allocation Question

I am working on a program that, for good reason, runs loooooong.  I am
looking through our account files to find matching accounts, where two
of Name, DOB, SS# match.  We frequently deal with the same client in
the same day, but create a new account for them (hospital
billing--long story).  My task seemed easy at first, so I wrote it as
follows:

-Create one file with all accounts 
-Start with the first record, compare it to all others
- Move to next record.  

This thing ran for hours and hours.  Then I calcd it (3,500,000 accts)
at somewhere over 12 trillion DB reads.  We have a fast machine, but
no.

My current version uses a user space, and a data structure, based on a
pointer, that moves through the 'records' in the user space to do the
comparison.  Also, we agreed to only search within each company.  This
brings the number down to 294 billion iterations.  Not bad, and the
user space is much faster.

But it is still slow.  Takes an entire day to run.  Even though this
will be run monthly, I am considering another strategy, using memory. 
I know that I can allocate memory, base a pointer on that memory, and
do the same thing I was doing to the user space to actual memory.  My
question is, what is the limit, and is there one.  What happens if I
end up alloc'ing ~10Meg?  Does this seem like a reasonable strategy? 
Will it be faster?


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