ORA-01502 state unusable錯誤成因和解決方法(二)
2024-07-21 02:40:31
供稿：網友
SQL> create table t(a number);
Table created.
現在，我們建立一個唯一索引來看看：
SQL> create unique index idx_t on t(a);
Index created.
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='T';
no rows selected
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='IDX_T';
INDEX_NAME INDEX_TYPE TABLESPACE_NAME TABLE_TYPE STATUS
------------------------------ --------------------------- ------------------------------ ----------- --------
IDX_T NORMAL DATA_DYNAMIC TABLE VALID
SQL> insert into t values(1);
1 row created.
SQL> commit;
Commit complete.
將索引手工修改為unusable狀態（模擬發生索引失效的情況）：
SQL> alter index idx_t unusable;
Index altered.
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='IDX_T';
INDEX_NAME INDEX_TYPE TABLESPACE_NAME TABLE_TYPE STATUS
------------------------------ --------------------------- ------------------------------ ----------- --------
IDX_T NORMAL DATA_DYNAMIC TABLE UNUSABLE
我們看到這是，已經不能正常往表中插入數據：
SQL> insert into t values(2);
insert into t values(2)
*
ERROR at line 1:
ORA-01502: index 'MISC.IDX_T' or partition of sUCh index is in unusable state
首先，我們通過重建索引（rebuild index）的方法來解決問題：
SQL> alter index idx_t rebuild;
Index altered.
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='IDX_T';
INDEX_NAME INDEX_TYPE TABLESPACE_NAME TABLE_TYPE STATUS
------------------------------ --------------------------- ------------------------------ ----------- --------
IDX_T NORMAL DATA_DYNAMIC TABLE VALID
SQL> insert into t values(2);
1 row created.
SQL> commit;
Commit complete.
SQL>
現在我們再次模擬索引失效(unusable狀態)：
SQL> alter index idx_t unusable;
Index altered.
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='IDX_T';
INDEX_NAME INDEX_TYPE TABLESPACE_NAME TABLE_TYPE STATUS
------------------------------ --------------------------- ------------------------------ ----------- --------
IDX_T NORMAL DATA_DYNAMIC TABLE UNUSABLE
SQL> insert into t values(3);
insert into t values(3)
*
ERROR at line 1:
ORA-01502: index 'MISC.IDX_T' or partition of such index is in unusable state
然后，看看是否可以通過設置參數skip_unusable_indexes=true來解決問題：
SQL> alter session set skip_unusable_indexes=true;
Session altered.
SQL> insert into t values(3);
insert into t values(3)
*
ERROR at line 1:
ORA-01502: index 'MISC.IDX_T' or partition of such index is in unusable state
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='IDX_T';
INDEX_NAME INDEX_TYPE TABLESPACE_NAME TABLE_TYPE STATUS
------------------------------ --------------------------- ------------------------------ ----------- --------
IDX_T NORMAL DATA_DYNAMIC TABLE UNUSABLE
SQL> alter index idx_t rebuild;
Index altered.
SQL> select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='IDX_T';
INDEX_NAME INDEX_TYPE TABLESPACE_NAME TABLE_TYPE STATUS
------------------------------ --------------------------- ------------------------------ ----------- --------
IDX_T NORMAL DATA_DYNAMIC TABLE VALID
SQL> insert into t values(3);
1 row created.
SQL> commit;
Commit complete.
SQL>
很顯然，對于unique index，通過簡單的設置參數是不能解決問題的，要解決unique index 失效的問題，只能通過重建索引來實現。
