RE: Understanding User Indexes from RPG

I think the APIs are in the SEPT nowadays so they should be pretty fast.
Obviously there's a bit of overhead as IBM checks for errors in the parm list,
and other things--things you would normally do if you used MI directly.
So would MI be "faster" yes, but would it be appreciably fast, probably not.
Yes adding multiples at once is much less overhead than adding them one at a
time.

As to the other comments people have made regarding sorting, I think if you
exceed around 1000 entries, user indexes are always going to be faster than
sorting and searching. Under 1000 entries, sorting and search is going to beat
the index method proportionately as the number of entries approaches zero. 

-Bob Cozzi
www.i5PodCast.com
Ask your manager to watch i5 TV



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On
Behalf Of Steve Moland
Sent: Thursday, March 15, 2007 9:43 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: RE: Understanding User Indexes from RPG

Hi Bob,

 Wow, you comment was amazingly spot on to something I've got to add to
an application.

I've used user indexes a number of times to replace run time tables
which were used cut down on the time disk "chains" take. I've found the
indexes to be much faster than using keyed disk files though I always
thought of user indexes as just being the built-in access method that a
"chain" in RPG would use. 

Anyway the largest user index I've used was about 60,000  17 byte
entries (all 17 were the key). Existence in the index was all that
mattered.

I've a new need to use them but the number of entries will be from
700,000 to a few million, so I've been thinking of the index creation
time. Shouldn't have to be done all that often but enough for me to be
thinking performance. 

Currently I load the index 100 entries per API call which seemed to be
much faster than an API call for every entry. For 60,000 entries the
time seemed long.

Will using MI be appreciably faster on the load portion.
Will the retrieval be faster as well though using the API appears to
instantaneous.
DO you have any sample code for using MI stuff in RPG.

Regards

Steve Moland
Access Paths Inc
12 Parmenter Rd Unit C4
Londonderry NH 03053
603 845-0190 Ext 2
steve@xxxxxxxxxxx

------------------------------

message: 9
date: Thu, 15 Mar 2007 08:26:53 -0500
from: "Bob Cozzi" <bob@xxxxxxxxxxxx>
subject: RE: Understanding User Indexes from RPG

Recently I used RPG and the APIs but I  moved to using the MI

instructions in RPG to access index entries.

The best place to read about these things is in the MI 
instructions for
Independent Indexes. 
Some MI instructions are:
CRTINX
INSINXEN
FNDINXEN