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  • 【测试】使用hr用户下的employees和departments表写一条SQL语句,(MG连接)

    SQL> select * from employees d, departments t where d.department_id=t.department_id;
    
    106 rows selected.
    
    
    Execution Plan
    ----------------------------------------------------------
    Plan hash value: 1343509718
    
    --------------------------------------------------------------------------------
    ------------
    
    | Id  | Operation                    | Name        | Rows  | Bytes | Cost (%CPU)
    | Time     |
    
    --------------------------------------------------------------------------------
    ------------
    
    |   0 | SELECT STATEMENT             |             |   106 |  9540 |     6  (17)
    | 00:00:01 |
    
    |   1 |  MERGE JOIN                  |             |   106 |  9540 |     6  (17)
    | 00:00:01 |
    
    |   2 |   TABLE ACCESS BY INDEX ROWID| DEPARTMENTS |    27 |   567 |     2   (0)
    | 00:00:01 |
    
    |   3 |    INDEX FULL SCAN           | DEPT_ID_PK  |    27 |       |     1   (0)
    | 00:00:01 |
    
    |*  4 |   SORT JOIN                  |             |   107 |  7383 |     4  (25)
    | 00:00:01 |
    
    |   5 |    TABLE ACCESS FULL         | EMPLOYEES   |   107 |  7383 |     3   (0)
    | 00:00:01 |
    
    --------------------------------------------------------------------------------
    ------------
    
    
    Predicate Information (identified by operation id):
    ---------------------------------------------------
    
       4 - access("D"."DEPARTMENT_ID"="T"."DEPARTMENT_ID")
           filter("D"."DEPARTMENT_ID"="T"."DEPARTMENT_ID")
    
    
    Statistics
    ----------------------------------------------------------
              8  recursive calls
              0  db block gets
             20  consistent gets
              0  physical reads

     

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  • 原文地址:https://www.cnblogs.com/tomatoes-/p/5971003.html
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