Question

目前我正在使用oracle 11g中的type对象。在这里我有DB对象如下：

表

CREATE TABLE students
  (rollno NUMBER(15) primary key, s_Name VARCHAR2(20), Marks type_1
  );

类型对象规范是

CREATE OR REPLACE type type_1
AS
  object
  (
    sub_1 NUMBER,
    sub_2 NUMBER,
    sub_3 NUMBER,
    member FUNCTION total
    RETURN NUMBER,
    member FUNCTION e_result
    RETURN VARCHAR2);

它的身体

CREATE OR REPLACE type body type_1
AS
  member FUNCTION total
  RETURN NUMBER
IS
BEGIN
  RETURN (sub_1+sub_2+sub_3);
END;
member FUNCTION e_result
  RETURN VARCHAR2
IS
  DECLARE
    temp NUMBER;
  BEGIN
    temp  :=sub_1+sub_2+sub_3;
    IF(temp>50) THEN
      RETURN ('pass');
    ELSE
      RETURN ('fail');
    END IF;
  END;
END;

创建了所有这些东西之后，即使我已经使用

BEGIN
FOR i IN 1..800 LOOP
        FOR j IN 1..400 LOOP
INSERT INTO students
VALUES     (sequence1.NEXTVAL,
            dbms_random.String('A', 5),
            Type_1(Round(dbms_random.Value(10, 100)), Round(
            dbms_random.Value(10, 100)), Round(dbms_random.Value(10, 100))));
END LOOP;
END LOOP;

dbms_output.Put_line('completed');

COMMIT;
END;

/

我需要在e_result列上创建位图索引，在tot列上创建普通索引。

我试过了

create index id1 on students(marks.total)

和

create bitmap index bid1 on students(marks.e-result)

但我不能。我该怎么办？

Answer 1

首先，您必须将您的函数声明为DETERMINISTIC，以便在SQL索引中使用它们（即，您必须断言给Oracle提供相同的输入，它们会提供相同的输出）。

例如：

SQL> CREATE OR REPLACE type type_1
  2  AS
  3    object
  4    (
  5      sub_1 NUMBER,
  6      sub_2 NUMBER,
  7      sub_3 NUMBER,
  8      member FUNCTION total
  9      RETURN NUMBER deterministic,
 10      member FUNCTION e_result
 11      RETURN VARCHAR2 deterministic
 12  );
 13  /

Type created.

SQL> CREATE OR REPLACE type body type_1
  2  AS
  3    member FUNCTION total
  4    RETURN NUMBER deterministic
  5  IS
  6  BEGIN
  7    RETURN (sub_1+sub_2+sub_3);
  8  END;
  9  member FUNCTION e_result
 10    RETURN VARCHAR2 deterministic
 11  IS
 12      temp NUMBER;
 13    BEGIN
 14      temp  :=sub_1+sub_2+sub_3;
 15      IF(temp>50) THEN
 16        RETURN ('pass');
 17      ELSE
 18        RETURN ('fail');
 19      END IF;
 20    END;
 21  END;
 22  /

其次，你必须在调用函数时使用()，否则它将假定它是一个名为total的列：

SQL> create index id1 on students (marks.total());

Index created.

SQL> create bitmap index bid1 on students(marks.e_result());

Index created.

然后您应该看到使用的索引：

SQL> exec dbms_stats.gather_table_stats(user, 'STUDENTS', method_opt=>'for all indexed columns size skewonly')

PL/SQL procedure successfully completed.

SQL> explain plan for select * from students s where s.marks.e_result() = 'fail';

Explained.

SQL> @explain ""

Plan hash value: 1595221732

-----------------------------------------------------------------------------------------
| Id  | Operation                    | Name     | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |          |   635 | 17780 |   109   (0)| 00:00:02 |
|   1 |  TABLE ACCESS BY INDEX ROWID | STUDENTS |   635 | 17780 |   109   (0)| 00:00:02 |
|   2 |   BITMAP CONVERSION TO ROWIDS|          |       |       |            |          |
|*  3 |    BITMAP INDEX SINGLE VALUE | BID1     |       |       |            |          |
-----------------------------------------------------------------------------------------

如何在类型对象上创建索引？

1 个答案: