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我们在编译INVALID的同义词(synonym)的时候，可能在某些版本会遇到一些特殊权限问题，具体来说是遇到ORA-01031错误。下面构造这样一个例子：
如下所示，scott用户下面创建了一个公共同义词emp(下面测试环境为Oracle 10.2.0.5)
- SQL> show user;
- USER is "SCOTT"
- SQL> create public synonym emp for scott.emp;
- Synonym created.
- SQL>
假设我们需要重新编译同义词，在system用户下去编译同义词时，就会遇到ORA-01031
- SQL> show user;
- USER is "SYSTEM"
- SQL> alter public synonym emp compile;
- alter public synonym emp compile
- *
- ERROR at line 1:
- ORA-01031: insufficient privileges
另外一种情况也会遇到这个错误，UserA 去编译UserB下的同义词的话，也会遇到这个错误。按照我的理解，如果用户拥有CREATE ANY SYNONYM和DROP ANY SYNONYM权限的话，应该是可以编译其它SCHEMA下的同义词。而且SYSTEM用户被授予了DBA角色，DBA角色拥有CREATE ANY SYNONYM 或DROP ANY SYNONYM的权限。
- SQL> SELECT * FROM DBA_SYS_PRIVS WHERE PRIVILEGE IN('CREATE ANY SYNONYM','DROP ANY SYNONYM') AND GRANTEE='DBA';
- GRANTEE PRIVILEGE ADM
- ------------------------------ ---------------------------------------- ---
- DBA DROP ANY SYNONYM YES
- DBA CREATE ANY SYNONYM YES
- SQL> SELECT * FROM DBA_ROLE_PRIVS WHERE GRANTEE='SYSTEM';
- GRANTEE GRANTED_ROLE ADM DEF
- ------------------------------ ------------------------------ --- ---
- SYSTEM AQ_ADMINISTRATOR_ROLE YES YES
- SYSTEM DBA YES YES
- SYSTEM MGMT_USER NO YES
但是metalink上的文档Doc ID 1299001.1提示：同义词的编译时，要么是sys用户或者同义词的OWNER才能编译，也就是说，你要编译同义词emp，必须是scott用户或sys用户。
- SQL> show user
- USER is "SYS"
- SQL> alter public synonym emp compile;
- Synonym altered.
所以在Oracle 10g下要编译其它schema下的同义词，必须是sys用户。Ora-01031 When Compiling A Synonym (Doc ID 1299001.1)的介绍如下：
文档Ora-01031 When Executing Alter Synonym Compile For Other Schema (Doc ID 1435898.1)中也有相关简单阐述
在Oracle 11.2.0.4.0中测试也是如此。但是后续官方文档中将这个现象视为一个Bug，官方文档4189542 - Only SYS can "alter synonym... compile" for another users's synonym (Doc ID 4189542.8)中有简单介绍，并且在后面的一些版本中修复了这个Bug，Doc ID 4189542.8的具体信息如下如下：
- Only SYS can "alter synonym... compile" for another users's synonym.
- Other users get ORA-1031 attempting to compile another users synonym.
- With this fix a user with both CREATE ANY SYNONYM and DROP ANY SYNONYM
- privilege is allowed to issue ALTER SYNONYM .. COMPILE for another users synonym.
相同的现象在不同文档中有不同阐述，确实有点让人迷惑，如果获取的信息不全或比较片面的话，可能会对这个问题和现象有不同的理解。
参考资料：
Ora-01031 When Compiling A Synonym (Doc ID 1299001.1)
Ora-01031 When Executing Alter Synonym Compile For Other Schema (Doc ID 1435898.1)
Bug 4189542 - Only SYS can "alter synonym... compile" for another users's synonym (Doc ID 4189542.8)
