Unexpected performance finding with MOVE-CORRESPONDING between table and structure variant

During some tests with a huge amount of data a a colleague of me Dirk Freundel gets unexpected performance finding between:

MOVE-CORRESPONDING struc1 TO struc2
MOVE-CORRESPONDING itab1 TO itab2

He put 1.000.000 lines of a table with 27 columns into a internal table with 16 columns. Variant 1 needed about 179 ms less time than variant 2.

Test code:

DO 10 TIMES.

*   Init
    FREE lt_middle.

*   Runtime
    GET RUN TIME FIELD lv_runtime_a.

*   LOOP
    LOOP AT lt_database ASSIGNING <fs_database>.   

        MOVE-CORRESPONDING <fs_database> TO ls_middle.     
        INSERT ls_middle INTO TABLE lt_middle.

    ENDLOOP.

*   OR TABLE
    "MOVE-CORRESPONDING lt_database TO lt_middle.

*   Runtime
    GET RUN TIME FIELD lv_runtime_b.
    lv_runtime_b = ( lv_runtime_b - lv_runtime_a ) / 1000.
    WRITE: / SY-INDEX, ' Runtime [msec]: ', lv_runtime_b.

ENDDO.

Has anybody else observed the same performance finding, Please add a comment.

2 Comments

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Eyann Zen

March 23, 2017 at 8:38 am

Hi Florian .Your code kind of confuses me .To me itab1 itab2 struc1 struc2 are the same things .They are all work area. Maybe it's coincidence ??^^

Former Member

March 23, 2017 at 9:57 am

Hi Eyann,

I came to this when I had the requirement to copy data from itab1 (lt_database) to itab2 (lt_middle). lt_database has 27 fields, lt_middle just has 16 fields. So there are two possibilities:

LOOP AT lt_database an use MOVE-CORRESPONDING ls_database ("struc1") TO ls_middle ("struc2")
MOVE-CORRESPONDING lt_database ("itab1") TO lt_middle ("itab2")

I think the "MOVE-CORRESPONDING itab1 TO itab2" is a rather new ABAP command, while "MOVE-CORRESPONDING struc1 TO struc2" is very old - so I thought/ hoped that the new command has performance advantages over the old LOOP & MOVE...

Unexpected performance finding with MOVE-CORRESPONDING between table and structure variant

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