parallel cursor

Former Member — Thu, 04 Aug 2005 12:29:21 GMT

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

Re: parallel cursor

andreas_mann3 — Thu, 04 Aug 2005 12:49:32 GMT

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

Re: parallel cursor

ChristianFi — Thu, 04 Aug 2005 13:06:23 GMT

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

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parallel cursor

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