内表访问表达式是ABAP 7.4中引入的重要特性，可以使语句变得更加简洁、美观。那么它的读写性能怎么样呢？我进行了一点点测试。
读取
测试代码，使用三种方式读取同一内表，分别是read table关键字、表达式和read table...binary search：
REPORT ztest_read.
DATA: BEGIN OF gs_test,
index TYPE i,
des TYPE string,
END OF gs_test.
DATA: gt_test LIKE STANDARD TABLE OF gs_test.
CLASS zcl_reader DEFINITION.
PUBLIC SECTION.
METHODS:
constructor IMPORTING itab LIKE gt_test,
read_by_read,
read_by_exp,
read_by_binary.
PRIVATE SECTION.
DATA: lt_test LIKE STANDARD TABLE OF gs_test.
CLASS-DATA index1 TYPE i VALUE 3769.
CLASS-DATA index2 TYPE i VALUE 5555.
ENDCLASS.
CLASS zcl_reader IMPLEMENTATION.
METHOD constructor.
lt_test = itab.
ENDMETHOD.
METHOD read_by_read.
READ TABLE lt_test WITH KEY index = index1 INTO DATA(ls_test).
READ TABLE lt_test WITH KEY index = index2 INTO ls_test.
ENDMETHOD.
METHOD read_by_exp.
DATA(ls_test) = lt_test[ index = index1 ].
ls_test = lt_test[ index = index2 ].
ENDMETHOD.
METHOD read_by_binary.
READ TABLE lt_test WITH KEY index = index1 INTO DATA(ls_test) BINARY SEARCH.
READ TABLE lt_test WITH KEY index = index2 INTO ls_test BINARY SEARCH.
ENDMETHOD.
ENDCLASS.
INITIALIZATION.
DATA(des) = ‘一个字符串‘.
DO 30000 TIMES.
gs_test-index = gs_test-index + 1.
gs_test-des = des.
APPEND gs_test TO gt_test.
ENDDO.
DATA(gr_reader) = NEW zcl_reader( gt_test ).
gr_reader->read_by_read( ).
gr_reader->read_by_exp( ).
gr_reader->read_by_binary( ).
结果：
如图，内表访问表达式在修改方面的性能和read是一样的。
修改
测试代码，分别使用modify关键字，内表访问表达式，field symbol来修改内表：
*&---------------------------------------------------------------------*
*& Report ZTEST_ITAB_MODIFY
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*
REPORT ztest_itab_modify.
DATA: BEGIN OF gs_test,
index TYPE i,
des TYPE string,
END OF gs_test.
DATA: gt_test LIKE STANDARD TABLE OF gs_test.
CLASS zcl_editor DEFINITION.
PUBLIC SECTION.
METHODS:
constructor IMPORTING itab LIKE gt_test,
modify_by_modify,
modify_by_exp,
modify_by_fs.
PRIVATE SECTION.
CLASS-DATA new_string TYPE string VALUE ‘喵喵喵?‘.
DATA: lt_test1 LIKE STANDARD TABLE OF gs_test.
DATA: lt_test2 LIKE STANDARD TABLE OF gs_test.
DATA: lt_test3 LIKE STANDARD TABLE OF gs_test.
ENDCLASS.
CLASS zcl_editor IMPLEMENTATION.
METHOD constructor.
lt_test1 = itab.
lt_test2 = itab.
lt_test3 = itab.
ENDMETHOD.
METHOD modify_by_modify.
DATA idx TYPE i VALUE 1.
DO lines( lt_test1 ) TIMES.
READ TABLE lt_test1 INTO DATA(ls_test) INDEX idx .
ls_test-des = new_string.
MODIFY lt_test1 FROM ls_test INDEX idx.
idx = idx + 1.
ENDDO.
ENDMETHOD.
METHOD modify_by_exp.
DATA idx TYPE i VALUE 1.
DO lines( lt_test2 ) TIMES.
lt_test2[ idx ]-des = new_string.
idx = idx + 1.
ENDDO.
ENDMETHOD.
METHOD modify_by_fs.
DATA idx TYPE i VALUE 1.
FIELD-SYMBOLS: <fs> LIKE gs_test.
DO lines( lt_test3 ) TIMES.
READ TABLE lt_test1 ASSIGNING <fs> INDEX idx .
<fs>-des = new_string.
idx = idx + 1.
ENDDO.
ENDMETHOD.
ENDCLASS.
INITIALIZATION.
DATA(des) = ‘一个字符串‘.
DO 30000 TIMES.
gs_test-index = gs_test-index + 1.
gs_test-des = des.
APPEND gs_test TO gt_test.
ENDDO.
DATA(lr_editor) = NEW zcl_editor( gt_test ).
lr_editor->modify_by_modify( ).
lr_editor->modify_by_exp( ).
lr_editor->modify_by_fs( ).
结果：
可以看出，内表访问表达式在修改普通的标准表时的性能是要稍差于modify关键字的。更不如field symbol。
当然，本文中使用的例子不能代表实际业务场景，因此只可以用作参考。
时间： 2024-10-06 22:16:54