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分享一篇运维DBA需求，创建含sysdate的函数index案例

1.模拟Oracle数据库环境

创建表插入数据库

[oracle@node1 ~]$ sqlplus chf/oracleplus

SQL*Plus: Release 11.2.0.3.0 Production on Mon Jan 9 16:27:19 2012

Copyright (c) 1982, 2011, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

With the Partitioning, Oracle Label Security, OLAP, Data Mining,

Oracle Database Vault and Real Application Testing options

SQL> create table t_oracleplus(id number,intime date);

Table created.

SQL> DECLARE

2 i NUMBER;

3 BEGIN

4 FOR i IN 1..1000 LOOP

5 INSERT INTO t_oracleplus VALUES(i,SYSDATE-i);

6 END LOOP;

7 COMMIT;

8 END;

9 /

PL/SQL procedure successfully completed.

SQL> select count(*) from t_oracleplus;

COUNT(*)

----------

1000

SQL> exec dbms_stats.gather_table_stats(USER,'T_oracleplus',cascade => TRUE);

PL/SQL procedure successfully completed.

2.无index查询

SQL> set autot trace exp stat

Execution Plan

----------------------------------------------------------

Plan hash value: 548923532

--------------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |

--------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 10 | 120 | 3 (0)| 00:00:01 |

|* 1 | TABLE ACCESS FULL| T_oracleplus | 10 | 120 | 3 (0)| 00:00:01 |

--------------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

1 - filter(NVL("INTIME",SYSDATE@!)>=TO_DATE(' 2011-12-31 00:00:00',

'syyyy-mm-dd hh24:mi:ss'))

Statistics

----------------------------------------------------------

0 recursive calls

0 db block gets

7 consistent gets

0 physical reads

0 redo size

770 bytes sent via SQL*Net to client

519 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

9 rows processed

SQL> set autot off

这里只是做了一个简单的查询，因为这个nvl(intime,sysdate)的条件，无法使用正常的index，所以没有建立intime索引的测试。

3.尝试创建index

SQL> create index in_t_oracleplus on t_oracleplus (nvl(intime,sysdate)) online nologging;

create index in_t_oracleplus on t_oracleplus (nvl(intime,sysdate)) online nologging

*

ERROR at line 1:

ORA-01743: only pure functions can be indexed

SQL> !oerr ora 1743

01743, 00000, "only pure functions can be indexed"

// *Cause: The indexed function uses SYSDATE or the user environment.

// *Action: PL/SQL functions must be pure (RNDS, RNPS, WNDS, WNPS). SQL

// expressions must not use SYSDATE, USER, USERENV(), or anything

// else dependent on the session state. NLS-dependent functions

// are OK.

--因为含有sysdate创建函数index失败

SQL> CREATE OR REPLACE FUNCTION f_oracleplus (itime DATE)

2 RETURN DATE

3 IS

4 otime DATE;

5 BEGIN

6 otime:=NVL(itime,SYSDATE);

7 RETURN otime;

8 END;

9 /

Function created.

--想采用自定义函数屏蔽掉sysdate在创建index时候的影响

SQL> create index in_t_oracleplus on t_oracleplus (f_oracleplus(intime)) online nologging;

create index in_t_oracleplus on t_oracleplus (f_oracleplus(intime)) online nologging

*

ERROR at line 1:

ORA-30553: The function is not deterministic

SQL> !oerr ora 30553

30553, 00000, "The function is not deterministic"

// *Cause: The function on which the index is defined is not deterministic

// *Action: If the function is deterministic, mark it DETERMINISTIC. If it

// is not deterministic (it depends on package state, database state,

// current time, or anything other than the function inputs) then

// do not create the index. The values returned by a deterministic

// function should not change even when the function is rewritten or

// recompiled.

--因为函数缺少deterministic不能使用于index上

SQL> CREATE OR REPLACE FUNCTION f_oracleplus (itime DATE)

2 RETURN DATE deterministic

3 IS

4 otime DATE;

5 BEGIN

6 otime:=NVL(itime,SYSDATE);

7 RETURN otime;

8 END;

9 /

Function created.

SQL> create index in_t_oracleplus on t_oracleplus (f_oracleplus(intime)) online nologging;

Index created.

--创建函数index成功

SQL> exec dbms_stats.gather_table_stats(USER,'T_oracleplus',cascade => TRUE);

PL/SQL procedure successfully completed.

4.再次查询

确定已经使用函数index，达到在index中使用sysdate函数index的目的。

SQL> set autot on exp stat

SQL> select * from t_oracleplus where f_oracleplus(intime)>=to_date('2011-12-31','yyyy-mm-dd');

Execution Plan

----------------------------------------------------------

Plan hash value: 2005404611

---------------------------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |

---------------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 10 | 200 | 3 (0)| 00:00:01 |

| 1 | TABLE ACCESS BY INDEX ROWID| T_oracleplus | 10 | 200 | 3 (0)| 00:00:01 |

|* 2 | INDEX RANGE SCAN | IN_T_oracleplus | 10 | | 2 (0)| 00:00:01 |

---------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

2 - access("CHF"."F_oracleplus"("INTIME")>=TO_DATE(' 2011-12-31 00:00:00',

'syyyy-mm-dd hh24:mi:ss'))

Statistics

----------------------------------------------------------

0 recursive calls

0 db block gets

5 consistent gets

0 physical reads

0 redo size

770 bytes sent via SQL*Net to client

519 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

9 rows processed

5.总结说明

5.1)通过函数屏蔽函数index的时候，不能使用sysdate

5.2)在创建函数时，需要指定deterministic关键字

--------------------------------------ORACLE-DBA----------------------------------------

最权威、专业的Oracle案例资源汇总之【学习笔记】Oracle索引 创建含sysdate的函数index案例