Reference variable、Workarea 和 Field-Symbols性能比较

在ABAP release 610版本之后，就支持REFERENCE INTO语法了，REFERENCE INTO常用在内表操作LOOP、READ语句中。

简单的case：

1. DATA: t_t100 TYPE STANDARD TABLE OF t100.
   
2. DATA: lr_t100 TYPE REF TO t100.                " << Reference variable
   
3. 
   
4. SELECT *
   
5.   FROM t100 INTO TABLE t_t100 UP TO 10 ROWS.
   
6. 
   
7. LOOP AT t_t100 REFERENCE INTO lr_t100.         " << working with it
   
8.   WRITE: / lr_t100->msgnr.                     " << Accessing the component
   
9.   lr_t100->msgnr = '999'.
   
10. 
    
11. ENDLOOP.
    
12. 
    
13. LOOP AT t_t100 REFERENCE INTO lr_t100.
    
14.   WRITE: / lr_t100->msgnr.
    
15. ENDLOOP.

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Reference variable、Workarea 和 Field-Symbols的Performance测试案例：

1. DATA: i_bseg TYPE STANDARD TABLE OF bseg,
   
2.       wa_bseg LIKE LINE OF i_bseg.
   
3. 
   
4. DATA: lv_flag TYPE flag,
   
5.       lv_sta_time TYPE timestampl,
   
6.       lv_end_time TYPE timestampl,
   
7.       lv_diff_w   TYPE p DECIMALS 5,
   
8.       lv_diff_f   LIKE lv_diff_w,
   
9.       lv_diff_r   LIKE lv_diff_w,
   
10.       lv_save     LIKE lv_diff_w.
    
11. 
    
12. FIELD-SYMBOLS: <fs_bseg> LIKE LINE OF i_bseg.
    
13. 
    
14. DATA: o_bseg TYPE REF TO bseg.
    
15. 
    
16. * data selection = 100,000 records
    
17. SELECT * FROM bseg INTO TABLE i_bseg UP TO 100000 ROWS.
    
18. 
    
19. * Begin - Processing with Work area
    
20. GET TIME STAMP FIELD lv_sta_time.
    
21. LOOP AT i_bseg INTO wa_bseg.
    
22.   IF lv_flag = 'X'.
    
23.     wa_bseg-sgtxt = 'TEST'.
    
24.     MODIFY i_bseg FROM wa_bseg.
    
25.   ENDIF.
    
26.   CLEAR wa_bseg.
    
27.   IF lv_flag IS INITIAL.
    
28.     lv_flag = 'X'.
    
29.   ENDIF.
    
30. ENDLOOP.
    
31. GET TIME STAMP FIELD lv_end_time.
    
32. lv_diff_w = lv_end_time - lv_sta_time.
    
33. WRITE: /(30) 'Work area', lv_diff_w.
    
34. * End   - Processing with Work Area
    
35. 
    
36. CLEAR: lv_flag,
    
37.        lv_sta_time,
    
38.        lv_end_time.
    
39. * Begin - Processing with Field-Symbols
    
40. GET TIME STAMP FIELD lv_sta_time.
    
41. LOOP AT i_bseg ASSIGNING <fs_bseg>.
    
42.   IF lv_flag = 'X'.
    
43.     <fs_bseg>-sgtxt = 'TEST'.
    
44.   ENDIF.
    
45.   IF lv_flag IS INITIAL.
    
46.     lv_flag = 'X'.
    
47.   ENDIF.
    
48. ENDLOOP.
    
49. GET TIME STAMP FIELD lv_end_time.
    
50. lv_diff_f = lv_end_time - lv_sta_time.
    
51. WRITE: /(30) 'Field-Symbol', lv_diff_f.
    
52. * End   - Processing with FS
    
53. 
    
54. * Net time saving
    
55. lv_save = lv_diff_w - lv_diff_f.
    
56. WRITE: /(30) 'Total Save (FS-WA)', lv_save.
    
57. 
    
58. CLEAR: lv_flag,
    
59.        lv_sta_time,
    
60.        lv_end_time.
    
61. * Begin - Processing with Field-Symbols
    
62. GET TIME STAMP FIELD lv_sta_time.
    
63. LOOP AT i_bseg REFERENCE INTO o_bseg.
    
64.   IF lv_flag = 'X'.
    
65.     o_bseg->sgtxt = 'TEST'.
    
66.   ENDIF.
    
67.   IF lv_flag IS INITIAL.
    
68.     lv_flag = 'X'.
    
69.   ENDIF.
    
70. ENDLOOP.
    
71. GET TIME STAMP FIELD lv_end_time.
    
72. lv_diff_r = lv_end_time - lv_sta_time.
    
73. WRITE: /(30) 'Reference', lv_diff_r.
    
74. * End   - Processing with FS
    
75. 
    
76. * Net time saving
    
77. lv_save = lv_diff_f - lv_diff_r.
    
78. WRITE: /(30) 'Total Save(Ref-FS)', lv_save.
    
79. 
    
80. WRITE: / 'Done'.

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测试结果：

由此可见Field-Symbols性能最高，其次是Reference variable，最差的是Workarea，建议编程是多使用Field-Symbols，如果你喜欢oop，建议使用Reference variable。