sec@ora10g> desc t2; Name Null? Type --------------- -------- ------------------ X NOT NULL VARCHAR2(20)
sec@ora10g> select count(*) from t2;
COUNT(*) ---------- 0
3.保證在線重定義的順利執行，授予用戶所需要的權限。 sec@ora10g> conn / as sysdba Connected. sys@ora10g> grant EXECUTE_CATALOG_ROLE,CREATE ANY TABLE,ALTER ANY TABLE,DROP ANY TABLE,LOCK ANY TABLE,SELECT ANY TABLE to sec;
關于start_redef_table參數內容的表述請參考下面內容。 PROCEDURE START_REDEF_TABLE Argument Name Type In/Out Default? ------------------------------ ----------------------- ------ -------- UNAME VARCHAR2 IN ORIG_TABLE VARCHAR2 IN INT_TABLE VARCHAR2 IN COL_MAPPING VARCHAR2 IN DEFAULT OPTIONS_FLAG BINARY_INTEGER IN DEFAULT ORDERBY_COLS VARCHAR2 IN DEFAULT PART_NAME VARCHAR2 IN DEFAULT
4）看一下此時目標表T1和中間表T2的結構和數據 sec@ora10g> desc t1; Name Null? Type ------------------- -------- ---------------------- X NOT NULL NUMBER(19)
sec@ora10g> desc t2 Name Null? Type ------------------- -------- ---------------------- X NOT NULL VARCHAR2(20)
sec@ora10g> select count(*) from t1;
COUNT(*) ---------- 11944
sec@ora10g> select count(*) from t2;
COUNT(*) ---------- 11944
此時結構沒有變化，數據已經同步到中間表T2表中。
5）模擬目標表T1的事務（以刪除為例） sec@ora10g> delete from t1 where rownum<10000;
5.小結 在線重定義功能在保證系統高可用的前提下完成數據庫調整帶來了非常大的便利。 此文中描述的使用在線重定義修改主鍵類型的例子并不普遍，在線重定義功能主要還是集中在以下幾個場景： Online table redefinition enables you to:
* Modify the storage parameters of a table or cluster * Move a table or cluster to a different tablespace in the same schema * Add, modify, or drop one or more columns in a table or cluster * Add or drop partitioning support (non-clustered tables only) * Change partition structure * Change physical properties of a single table partition, including moving it to a different tablespace in the same schema * Change physical properties of a materialized view log or an Oracle Streams Advanced Queueing queue table * Add support for parallel queries * Re-create a table or cluster to reduce fragmentation * Change the organization of a normal table (heap organized) to an index-organized table, or do the reverse. * Convert a relational table into a table with object columns, or do the reverse. * Convert an object table into a relational table or a table with object columns, or do the reverse.
