Using Sorted table and Index while processing Internal tables

By Suresh Kumar Parvathaneni

There would have been many instances where we would have to process large entries in an internal table with a WHERE condition. This article is intended to demonstrate the comparison between three different methods in handling this situation.  

First Method: The normal method used by most of us. Standard internal table processing using WHERE condition

Second Method: Same as above, but here we would be using the Sorted table

Third Method: Sorted table and using the Index  

Following is the demo program illustrating the above three methods:

REPORT ZINTERNAL_TABLE_OPERATIONS.

* Program to find the best method in reading the internal tables
* Author: Suresh Kumar Parvathaneni

* Type declaration
TYPES:
  BEGIN OF TY_MARA,
    MATNR LIKE MARA-MATNR,
    MTART LIKE MARA-MTART,
  END OF TY_MARA.

* Internal table declaration
DATA:
  T_MARA TYPE STANDARD TABLE OF TY_MARA,
  T_MARA1 TYPE SORTED TABLE OF TY_MARA
          WITH NON-UNIQUE KEY MTART.

* Variable declaration
DATA:
  W_COUNTER TYPE I,
  W_RUNTIME1 TYPE I,
  W_RUNTIME2 TYPE I,
  W_TABIX LIKE SY-TABIX.

* Table workarea definition
DATA:
  WA_MARA TYPE TY_MARA.

SELECT MATNR                           " Material Number
       MTART                           " Material Type
  FROM MARA
  INTO TABLE T_MARA.

T_MARA1[] = T_MARA[].

* CASE 1: Processing internal table using LOOP..WHERE Condition

GET RUN TIME FIELD W_RUNTIME1.

LOOP AT T_MARA INTO WA_MARA WHERE MTART EQ 'FHMI'.
  ADD 1 TO W_COUNTER.
ENDLOOP.

GET RUN TIME FIELD W_RUNTIME2.
* Calculate Runtime
W_RUNTIME2 = W_RUNTIME2 - W_RUNTIME1.
WRITE W_RUNTIME2.

CLEAR W_COUNTER.

* CASE 2: Using a Sorted table

GET RUN TIME FIELD W_RUNTIME1.
LOOP AT T_MARA1 INTO WA_MARA WHERE MTART EQ 'FHMI'.
  ADD 1 TO W_COUNTER.
ENDLOOP.

GET RUN TIME FIELD W_RUNTIME2.
* Calculate Runtime
W_RUNTIME2 = W_RUNTIME2 - W_RUNTIME1.
WRITE W_RUNTIME2.

CLEAR W_COUNTER.

* CASE 3: Using INDEX on a sorted table

GET RUN TIME FIELD W_RUNTIME1.
READ TABLE T_MARA1 INTO WA_MARA WITH KEY MTART = 'FHMI'.
IF SY-SUBRC EQ 0.
  W_TABIX = SY-TABIX + 1.
  ADD 1 TO W_COUNTER.
  LOOP AT T_MARA1 INTO WA_MARA FROM W_TABIX.
    IF WA_MARA-MTART NE 'FHMI'.
      EXIT.
    ENDIF.
    ADD 1 TO W_COUNTER.
  ENDLOOP.
ENDIF.
GET RUN TIME FIELD W_RUNTIME2.
* Calculate Runtime
W_RUNTIME2 = W_RUNTIME2 - W_RUNTIME1.
WRITE W_RUNTIME2.

Following is the analysis report in microseconds, as per the data volume:  

Records: 21,390

Records: 132,693

Sorted table might have given a better performance here if the field in the WHERE condition is the first field in the internal table. However, from the above statistics, we can say that method 3 is better than the other 2 methods. In production environment, the data would be huge and the performance could be much improved with this simple technique.