Re: CHAIN Versus SETLL and READ When Data Needed

[Alan Shore <AlanShore@xxxxxxxx>]

Shannon - in my opinion (for what its worth --- and that quote is directly
form my wife) the answer unfortunately is ---
It depends
Will you get a lot more NOT founds than you will get more founds?
If the answer is YES, then the SETLL is the way to go
otherwise - if you get lot more founds than not founds, then the CHAIN is
the way to go.
Where the break point is, I'm not too sure, and I'm not too sure how you
would try and find out.



Alan Shore

NBTY, Inc
(631) 244-2000 ext. 5019
AShore@xxxxxxxx


rpg400-l-bounces@xxxxxxxxxxxx wrote on 02/28/2007 02:27:25 PM:

> I posed this question on MCPressOnline the other day but I would like to
> get more opinions on it so I'll post it here too.   A shop-standard
> hangs in the balance.
>
>
>
>    Assume that you have an RPG program that has logic such that you need
> to first see if some data is in a file, based on a key, and then if so,
> you do something with that data.
>
>
>
>    Further assume that this file has a complex key with three fields.
>
>
>
>     The program logic is such that you check the maximum number of keys
> for a match down to the minimum number of keys
>
>
>
>      Like this:
>
>
>
>               Key1    Klist
>
>                           Kfld              Fld1
>
>                           Kfld              Fld2
>
>                           Kfld              Fld3
>
>
>
>               Key2     Klist
>
>                           Kfld              Fld1
>
>                           Kfld              Fld2
>
>
>
>               Key3     Klist
>
>                            Kfld             Fld1
>
>
>
>
>
>    Which one of these logic blocks is most efficient?
>
>
>
>    Key1   Setll   file
>
>        If    %FOUND(file)
>
>                Key1   READE file
>
>                        Use Fields
>
>        Else
>
>           Key2    Setll  File
>
>             If   %FOUND(file)
>
>                      Key2 Use Fields
>
>            Else
>
>              Key3  Setll File
>
>                   If   %FOUND(file)
>
>                      Key3 READE file
>
>                Endif
>
>             Endif
>
>           Endif
>
>
>
>
>
>
>
> OR....
>
>
>
>                KEY1  Chain file
>
>                           If       %FOUND(file)
>
>                               Use fields
>
>                          Else
>
>               KEY2   Chain  file
>
>                           If      %FOUND(file)
>
>                               Use Fields
>
>                           Else
>
>               KEY3   Chain file
>
>                           If   %FOUND(file)
>
>                              Use Fields
>
>                          Endif
>
>                          Endif
>
>                          Endif
>
>
>
>
>
> My opinion is that the CHAIN is more efficient from both a
> coding/maintenance standpoint and from an I/O standpoint, but I'm open
> to opinions.
>
>
>
>
>
>
>
>
>
>
>
> --
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