parallel cursor

[Former Member]

can anyone tell me what is use of parallel cursor method?

[andreas_mann3]

hi,

you mean <a href="http://help.sap.com/saphelp_47x200/helpdata/en/fc/eb3b23358411d1829f0000e829fbfe/frameset.htm">Using a Cursor to Read Data</a> ?

Andreas

[ChristianFi]

I guess you are referring to the SE30 Tipps&Tricks

to avoid nested loops:

nestedLoop:
* Entries: 100 (ITAB1), 1000 (ITAB2)
* Line width: 100
* Both tables sorted by key K

LOOP AT ITAB1 INTO WA1.
  LOOP AT ITAB2 INTO WA2
                WHERE K = WA1-K.
    " ...
  ENDLOOP.
ENDLOOP.

parallel cursors:
* Entries: 100 (ITAB1), 1000 (ITAB2)
* Line width: 100
* Both tables sorted by key K

I = 1.
LOOP AT ITAB1 INTO WA1.
  LOOP AT ITAB2 INTO WA2 FROM I.
    IF WA2-K <> WA1-K.
      I = SY-TABIX.
      EXIT.
    ENDIF.

    " ...
  ENDLOOP.
ENDLOOP.

thats what the text says:

• If ITAB1 has n1 entries and ITAB2 has n2 entries, the time needed for

• the nested loop with the straightforward algorithm is O(n1 * n2),

• whereas the parallel cursor approach takes only O(n1 + n2) time.

• The above parallel cursor algorithm assumes that ITAB2 contains only

• entries also contained in ITAB1.

• If this assumption does not hold, the parallel cursor algorithm

• gets slightly more complicated, but its performance characteristics

• remain the same.

Christian