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Oracle并行添加主键的方法

2014-07-04 21:56  AlfredZhao  阅读(4789)  评论(0编辑  收藏  举报
环境:Oracle 11.2.0.3
需求:生产一张表由于前期设计不当,没有主键。现需要添加主键,数据量很大,想并行建立。
 
1.直接添加,提示ora-3001:未实施的功能;只能单线程建立主键
SQL> alter table t add constraint pk_t primary key (object_id) using index online parallel 2;

alter table t add constraint pk_t primary key (object_id) using index online parallel 2

ORA-03001: 未实施的功能

SQL> alter table t add constraint pk_t primary key (object_id) using index online;

Table altered

SQL> alter table t drop primary key;

Table altered
 
2.考虑先并行添加惟一性索引,再添加主键
SQL> create unique index pk_t on t(object_id) parallel 2 online;

Index created

SQL> alter table t add constraint pk_t primary key (object_id);

Table altered

SQL> alter index pk_t noparallel;

Index altered
 
3.对比主键和惟一性索引的区别
SQL> desc t
Name           Type          Nullable Default Comments
-------------- ------------- -------- ------- --------
OWNER          VARCHAR2(30)  Y                        
OBJECT_NAME    VARCHAR2(128) Y                        
SUBOBJECT_NAME VARCHAR2(30)  Y                        
OBJECT_ID      NUMBER                                 
DATA_OBJECT_ID NUMBER        Y                        
OBJECT_TYPE    VARCHAR2(19)  Y                        
CREATED        DATE          Y                        
LAST_DDL_TIME  DATE          Y                        
TIMESTAMP      VARCHAR2(19)  Y                        
STATUS         VARCHAR2(7)   Y                        
TEMPORARY      VARCHAR2(1)   Y                        
GENERATED      VARCHAR2(1)   Y                        
SECONDARY      VARCHAR2(1)   Y                        
NAMESPACE      NUMBER        Y                        
EDITION_NAME   VARCHAR2(30)  Y                        

SQL> alter table t drop primary key;

Table altered

SQL> desc t
Name           Type          Nullable Default Comments
-------------- ------------- -------- ------- --------
OWNER          VARCHAR2(30)  Y                        
OBJECT_NAME    VARCHAR2(128) Y                        
SUBOBJECT_NAME VARCHAR2(30)  Y                        
OBJECT_ID      NUMBER        Y                        
DATA_OBJECT_ID NUMBER        Y                        
OBJECT_TYPE    VARCHAR2(19)  Y                        
CREATED        DATE          Y                        
LAST_DDL_TIME  DATE          Y                        
TIMESTAMP      VARCHAR2(19)  Y                        
STATUS         VARCHAR2(7)   Y                        
TEMPORARY      VARCHAR2(1)   Y                        
GENERATED      VARCHAR2(1)   Y                        
SECONDARY      VARCHAR2(1)   Y                        
NAMESPACE      NUMBER        Y                        
EDITION_NAME   VARCHAR2(30)  Y                        
总结:
对于已有大量数据的表无法并行建立主键,可以先并行建立惟一性索引然后再加上主键。
主键不能为空,惟一性索引可以为空。