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Author's profile photo Former Member

LP21 / RLLNACH1 performance

Overview

We use LP21 / RLLNACH1 (WM replenishment for fixed bins) in background processing. We have defined background jobs with 3-6 steps which executes RLLNACH1 for different storage types and storage locations. Execution times for biggest storage location were between 45 and 90 minutes. The job is scheduled 6 times every day, which gives total execution time from 4,5 to 7 hours! Every job execution creates 100 – 150 transfer orders, so it should not last so long.

Problem cause

I checked source code and debug the program – it was not performing any long SELECT statements, but the most of the time spends in READ_MATERIAL_NEW_46 form.

I found instructions (RLLNACH1, lines 1461-1471):

LOOP AT inspl.
  LOOP AT p_mard
    WHERE matnr = inspl-matnr
        AND werks = werks
        AND lgort = inspl-lgort.
    EXIT.
  ENDLOOP.
  IF sy-subrc <> 0.
    DELETE inspl.
  ENDIF.
ENDLOOP.

In our case tables p_mard and inspl contain:

– p_mard[] – 511000 rows
– inspl[]     –   59000 rows

When we check definition of P_MARD table:

DATA: BEGIN OF P_MARD OCCURS 100.
    INCLUDE STRUCTURE MARD.
DATA: END OF P_MARD.

it appears to be a standard table.

It is obvious, that searching this table with simple LOOP is very inefficient.

Solution

I created a modification:

*{   REPLACE                                                                  1
*\   LOOP AT inspl.
*\     LOOP AT p_mard
*\       WHERE matnr = inspl-matnr
*\           AND werks = werks
*\           AND lgort = inspl-lgort.
*\       EXIT.
*\     ENDLOOP.
*\     IF sy-subrc <> 0.
*\       DELETE inspl.
*\     ENDIF.
*\   ENDLOOP.
*** RLLNACH1 performance
SORT p_mard[] BY matnr werks lgort.
  LOOP AT inspl.
    READ TABLE p_mard[]
      TRANSPORTING NO FIELDS
      WITH KEY matnr = inspl-matnr
                     werks = werks
                     lgort = inspl-lgort
      BINARY SEARCH.
        IF sy-subrc <> 0.
          DELETE inspl.
        ENDIF.
      ENDLOOP.
*** RLLNACH1 performance - end
*}   REPLACE 

Test results

Results of this change was very satisfactory.

Here are execution times before and after change:
– 5 days before
– 5 days after
– 6 executions every day

execution times before [s] after [s] after / before
MIN 2750 103 3,7%
MAX 5088 216 4,2%
AVG 3441 164 4,8%

As a result of the change described here, program execution time descreased over 25 times.

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      6 Comments
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      Author's profile photo Matthew Billingham
      Matthew Billingham
      This shows what results you can get with a little effort - perhaps you should pass this on to SAP support and get them to put it into the standard. That's assuming it isn't already a note.

      I'd've chosen a different route though - one that doesn't change the program data.

      data: lto_zzz_mard like sorted table of p_mard with non-unique key matnr werks lgort.
      insert lines of p_mard into table lto_zzz_mard.
      LOOP AT inspl.
      READ TABLE lto_zzz_mard
      TRANSPORTING NO FIELDS
      WITH TABLE KEY matnr = inspl-matnr
      werks = werks
      lgort = inspl-lgort.
      IF sy-subrc <> 0.
      DELETE inspl.
      ENDIF.
      ENDLOOP.
      clear lto_zzz_mard.

      If you know that p_mard contains only unique records (with respect to matnr, werks, lgort), you can define a HASHED table, that could be even faster.

      Author's profile photo Former Member
      Former Member
      Hi Matthew,

      good point - I just informed SAP support.

      You are right - with hashed table it could be even faster. There is also no need to use SELECT * - only key fields are used.

      I tried to modify only small piece of code - results were very good, but as You see - there are more lines, that could be changed.

      Regards,

      --
      Przemysław

      Author's profile photo Matthew Billingham
      Matthew Billingham
      I did a quick search for performance notes for RLLNACH1, and while there are a few, none of them touch this issue. So, your coding could now be part of standard SAP!

      Author's profile photo Former Member
      Former Member
      Hi

      Thanks for good analysis. I am a Basis Consultant. I would like to know which functional uses this program. Can you please tell the use of this code so that I can also check whether it can be used in my client.

      Thanks,
      Ranjith.

      Author's profile photo Matthew Billingham
      Matthew Billingham
      Look at the program in SE38, select attributes, and you'll see the application.
      Author's profile photo Former Member
      Former Member
      Hi Ranjith!

      Thank You for first comment 🙂

      This is WM functionality (WM replenishment for fixed bins) to create transfer orders between different storage types - check who is privileged to use LP21 or if You have the program scheduled in background.

      Regards,

      --
      Przemysław