Re: Usage of Indexes and its Effects on an RPG Program

[Keith Carpenter <carpcon@xxxxxxx>]

Brian,

Maybe the problem is simply be an application issue.

You indicated it can take up to 5 mins. to run your update subroutine
(#SRUPD).  Any idea how many records are being read and updated in this
routine ?

If inordinately high, you might check if you key list (KEYT22) is not
selecting more records than it needs to.


Keith




Brian Piotrowski wrote:
> Thanks, Greg.  I suspected that the READE was the problem.  I have posed
> this question in RPG-400 along with a snippet of code that appears to be
> the friction in our system.
> 
> Brian.
> 
> -----Original Message-----
> From: Fleming, Greg (ED) [mailto:GFLEMING@xxxxxxxxxxxxxxxxxxxx] 
> Sent: Wednesday, December 14, 2005 10:50 AM
> To: Midrange Systems Technical Discussion
> Subject: RE: Usage of Indexes and its Effects on an RPG Program
> 
> If you are using READE, then I think your PF must be keyed, which is
> just as good as having a logical file.  Check the source on your PF. 
> 
> As far as indexes go, if you are creating a new logical file, you have
> to actually name that logical file on the F spec in your RPG program and
> refer to it in your C specs.  
> 
> If you are talking about an SQL index, that's another matter with which
> I'm not very familiar, but I think that Embedded SQL would probably pick
> it up right away, but your regular RPG program won't use it at all.  It
> only uses what you tell it to use. 
> 
> On a wider note, it sounds like you are trying to improve performance.
> I've been preaching here a couple times in the last few weeks about the
> hazards of using READE over a large data set, since it doesn't read from
> a block of records in memory, but actually hits the file for every read.
> If performance is an issue, much better to setLL on your key, then use
> READ, and compare your records to your key fields with a few more lines
> of code.  It's uglier, but it goes faster.
> 
> 
> 
> 
>>-----Original Message-----
>>From: midrange-l-bounces+gfleming=evergladesdirect.com@xxxxxxxxxxxx
>>[mailto:midrange-l-bounces+gfleming=evergladesdirect.com@xxxxxxxxxxxx]
> 
> On
> 
>>Behalf Of Brian Piotrowski
>>Sent: Wednesday, December 14, 2005 10:38 AM
>>To: Midrange Systems Technical Discussion
>>Subject: Usage of Indexes and its Effects on an RPG Program
>>
>>Hi All,
>>
>>
>>
>>I have a physical file that has 20 fields and contains over 2,000,000
>>records.  In the current RPG program, it does a SETLL/READE on the data
>>based on a key (which is the first five fields in the record).
> 
> However,
> 
>>the READE command does not have an associated logical file - it is
> 
> using
> 
>>the straight PF (this program was written before my time, and I suspect
>>does not run as efficiently as it should).
>>
>>
>>
>>I went into the system (via Navigator) and added an index to this PF of
>>the fields that are in the key.  Now my question: when a new index is
>>created on a physical file, will an RPG program begin using it
>>automatically, or does the program need to be made aware of the index?
>>
>>
>>
>>Thanks!
>>
>>
>>Brian.
>>
>>
>>
>>-=-=-=-=-=-=-=-=-=-=-=-=-=-
>>
>>Brian Piotrowski
>>
>>Specialist - I.T.
>>
>>Simcoe Parts Service, Inc.
>>
>>PH: 705-435-7814
>>
>>FX: 705-435-6746
>>
>>-=-=-=-=-=-=-=-=-=-=-=-=-=-
>>
>>
>>
>>--
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