Need some input on comparision btw sorted and std table.

Question

Hi,
Just a small comparision on using standard table, sorted table, and sorted table using index in a loop with where conditions.
I just ran this report to find out the time taken and it is quite surprising. Case 3 of the program is quite faster than case2 and of course very fast than case1. any inputs on how this is possible???
output value :
try 1: 674, 192, 147 for 100 entries.
try 2: 603, 53 , 6 for 20 entries.
*C-- Small report to compare sorted and standard table.
REPORT  zloopcompare.
TYPES : BEGIN OF tp_marc,
          werks TYPE marc-werks,
          matnr TYPE marc-matnr,
        END OF tp_marc.
DATA : t_marc TYPE STANDARD TABLE OF tp_marc.
DATA : t_marc1 TYPE SORTED TABLE OF tp_marc
WITH NON-UNIQUE KEY werks matnr.
DATA : wa_marc TYPE tp_marc.
DATA : p1 TYPE i,
       p2 TYPE i.
DATA : l_tabix TYPE sy-tabix.
DATA : count TYPE i.
PARAMETERS : p_werks TYPE marc-werks OBLIGATORY.
SELECT werks matnr FROM marc
INTO TABLE t_marc1
UP TO 1000 ROWS.
t_marc[] = t_marc1[].
*Case1 - standard table with where condition.
GET RUN TIME FIELD p1.
LOOP AT t_marc INTO wa_marc
WHERE werks EQ p_werks.
ENDLOOP.
GET RUN TIME FIELD p2.
p2 = p2 - p1.
WRITE : / p2.
*Case2- sorted table sorted as per the where condition.
GET RUN TIME FIELD p1.
LOOP AT t_marc1 INTO wa_marc
WHERE werks EQ p_werks.
ENDLOOP.
GET RUN TIME FIELD p2.
p2 = p2 - p1.
WRITE : / p2.
*Case3- using index to get faster access.
GET RUN TIME FIELD p1.
READ TABLE t_marc1 INTO wa_marc WITH KEY werks = p_werks.
IF sy-subrc EQ 0.
  l_tabix = sy-tabix + 1.
  LOOP AT t_marc1 INTO wa_marc FROM l_tabix.
    IF wa_marc-werks NE p_werks.
      EXIT.
    ENDIF.
  ENDLOOP.
ENDIF.
GET RUN TIME FIELD p2.
p2 = p2 - p1.
WRITE : / p2.

Answer 1

HI sharath,
I just checked and executed the code :
1. case 1 and 2 are fine.
2. but 3 is not what u desire.
  <b>(in fact its not looping at all)</b>
3.  the code in case 3 is :
IF wa_marc-werks NE p_werks.
EXIT.
ENDIF.
So the loop goes inside ONLY ONCE,
and so, hence, its LIGHTNING FAST.
Please note that READ TABLE reads only
1 record.
4. ***************
Instead of NE
write this, and u will see that its not so fast.
<b>IF wa_marc-werks = p_werks.</b>
EXIT.
ENDIF.
regards,
amit m.