RE: Difference between Select and Omit in LF

["Bob Cozzi" <cozzi@xxxxxxxxx>]

Hi Peter,
Just to verify, are you using the DYNSLT in either file's DDS?
-Bob

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Peter Colpaert
Sent: Wednesday, May 12, 2004 4:03 AM
To: RPG400-L@xxxxxxxxxxxx
Subject: Difference between Select and Omit in LF

Hi group,

has anybody besides me noticed an enormous difference in performance when 
the following two logical files are read in the exact same RPGLE program - 
native SETLL and READ, no SQL:

A          R PSMAST                    PFILE(PSMAST)
A* 
A          K PSPACD 
A          K PSCSNO 
A          K PSCTNO 
A* 
A          S PSATFG                    COMP(EQ 'A') 
A          S PSSTCD                    COMP(LT '30')

as opposed to

A          R PSMAST                    PFILE(PSMAST)
A* 
A          K PSPACD 
A          K PSCSNO 
A          K PSCTNO 
A* 
A          O PSATFG                    COMP(NE 'A') 
A          O PSSTCD                    COMP(GE '30')

The 'omit' version seems about 10 times faster.  I haven't actually timed 
it, but the omit gives subsecond response, whereas the select takes upto 5 
seconds to retrieve approximately 35 records.

For what it's worth, the displayed data is of course identical in both 
versions of the file. I don't even need to recompile the program when I 
switch LF versions.

Is this performance difference normal, or am I missing something?

Thanks,

Peter Colpaert
iSeries Application Developer

Honda Europe NV
Langerbruggestraat 104
B-9000 GENT
Belgium
Peter.Colpaert@xxxxxxxxxxxx
Tel: +32 9 2501 334
Fax: +32 9 2501 231
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