RE: SQL Existence Check

["DeLong, Eric" <EDeLong@xxxxxxxxxxxxxxx>]

Nathan,

Better be careful..... You're not using any of the fields in the read record
format, so I *THINK* the compiler speeds up the program by not processing
unused fields.  Since you don't use any of them in your program, there's no
overhead related to moving the data into storage.  If you were actually
using some of those fields, I think you'd see more overhead than you saw on
this test.  (Sorry I can't test it right now....)

Eric DeLong
Sally Beauty Company
MIS-Sr. Programmer/Analyst
940-898-7863 or ext. 1863



-----Original Message-----
From: Nathan M. Andelin [mailto:nandelin@relational-data.com]
Sent: Tuesday, March 12, 2002 9:57 AM
To: midrange-l@midrange.com
Subject: Re: SQL Existence Check


> From: <David.X.Kahn@gsk.com>
> Nathan wrote:
>
> >> Why not use a CHAIN?
> >
> > You took the first thought that came to my mind and put it into
> > words <smile>.  Or, why not use SETLL for better performance?
>
> Because it's a fallacy. :-)
>
> Dave...

I wrote the following program to test CHAIN vs. SETLL.  It did surprise me
that CHAIN took only 13% more time.  That's not much difference.  Thank you
for pointing out the not-so-obvious.

     Ftestio    IF   E           K DISK

     D myKey           S             12A   Dim(10000)
     D i               S             10I 0
     D Now             S               Z
     D Then            S               Z
     D Secs            S             10I 0

      *-----------------------------------------------------------------

     C                   For       i = 1 to 10000
     C                   Read      testior
     C                   Eval      myKey(i) = tikey
     C                   EndFor

      *-----------------------------------------------------------------

     C                   Time                    Then
     C                   For       i = 1 to 10000
     C     myKey(i)      Setll     testio                                 70
     C                   EndFor

      *-----------------------------------------------------------------

     C                   Time                    Now
     C     Now           Subdur    Then          Secs:*MS
     C     Secs          Dsply

      *-----------------------------------------------------------------

     C                   Time                    Then
     C                   For       i = 1 to 10000
     C     myKey(i)      Chain     testior                            70
     C                   EndFor

      *-----------------------------------------------------------------

     C                   Time                    Now
     C     Now           Subdur    Then          Secs:*MS
     C     Secs          Dsply

      *-----------------------------------------------------------------

     C                   SetOn                                        LR
     C                   Return

Nathan M. Andelin
www.relational-data.com


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