因此在使用前一定要首先检查第一个表是否为空,这一点很重要,否则会有performance问题。 如果For All Entries IN 字段修饰的内表很大的话,程序速度反而会减慢,而不是加快。因此应该尽量使该表的数据量控制在一个适当的大小。 不推荐使用: Loop at int_cntry. Select single * from zfligh into int_fligh where...
正确的方法不是用视图VIEW, 而是使用SELECT … INTO TABLE … FOR ALL ENTRIES IN 以及 READ TABLE WITH KEY BINARY SEARCH.例如我们要提高读取BSEG表的性能,首先我们会根据GJAHR主键从BKPF表取出部分数据到内表itab,然后使用FOR ALL ENTRIES IN itab WHERE BSEG~BELNR = itab~BELNR ...
如果For All Entries IN 字段修饰的内表是空表的话,源表的所有行都会被选入目标表中。因此在使用前一定要首先检查第一个表是否为空,这一点很重要,否则会有performance问题。 如果For All Entries IN 字段修饰的内表很大的话,程序速度反而会减慢,而不是加快。因此应该尽量使该表的数据量控制在一个适当的大小。
3. performance degradation when using the clause on big tables. In this post I'd like to shed some light on the third issue. Specifically i'll discuss the use of the "for all entries" clause as a means to join tables in the abap code instead of in db2. Say for example you have ...
8、使用table buffering Use of buffered tables is recommended to improve the performance considerably. The buffer is bypassed while using the following statementsSelect distinct Select … for update Order by, group by, having clause Joins Use the Bypass buffer addition to the select clause in order...
Select … for update Order by, group by, having clause Joins Use the Bypass buffer addition to the select clause in order to explicitly bypass the buffer while selecting the data. 9、 使用FOR ALL Entries 不推荐 Loop at int_cntry.
3. performance degradation when using the clause on big tables. In this post I'd like to shed some light on the third issue. Specifically i'll discuss the use of the "for all entries" clause as a means to join tables in the abap code instead of in db2. Say for example you have ...
要判断For all entries in后面的内表是否为空,如果它为空的话,那么在where条件中的与内表中字段进行比较的结果全部为真,也就是全部满足条件,这会导致取出非常多的数据,极大地影响系统的性能。** 6, 注意使用CORRESPONDING FIELDS OF 和 MOVE-CORRESPONDING 时候会进行字段比较, 带来CPU的开销大. ...
Whenever you need to use the FOR ALL ENTRIES, you must always consider getting unique keys first before doing the SELECT. It may appear unnecessary work, but believe me, it would save you lot of time. Refer to the statistics at end of this post to figure out the performance improvement....
if the itab used in the clause is empty , all the rows in the source table will be selected . 3. performance degradation when using the clause on big tables. In this post I'd like to shed some light on the third issue. Specifically i'll discuss the use of the "for all entries"...