rebuild和rebuild online的區別
2024-07-21 02:32:40
供稿：網友
SQL> eXPlain plan for
2 alter index test.IND_OBJECT_ID rebuild;Explained.SQL> select * from table(dbms_xplan.display);PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------- -------------------------------------------------------------------------
Id Operation Name Rows Bytes Cost
-------------------------------------------------------------------------
0 ALTER INDEX STATEMENT 6235 18705 10
1 INDEX BUILD NON UNIQUE IND_OBJECT_ID
2 SORT CREATE INDEX 6235 18705
3 INDEX FAST FULL SCAN IND_OBJECT_ID 6235 18705
-------------------------------------------------------------------------Note: cpu costing is off11 rows selected.SQL> explain plan for
2 alter index test.IND_OBJECT_ID rebuild online;Explained.SQL> select * from table(dbms_xplan.display);PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------------------------------------------------------------------------------
Id Operation Name Rows Bytes Cost
-------------------------------------------------------------------------
0 ALTER INDEX STATEMENT 6235 18705 10
1 INDEX BUILD NON UNIQUE IND_OBJECT_ID
2 SORT CREATE INDEX 6235 18705
3 TABLE access FULL T 6235 18705 10
-------------------------------------------------------------------------Note: cpu costing is off11 rows selected.SQL>可見rebuild 和rebuild online的掃描方式不同，但都會發生sort.在rebuild online 時會報錯ORA-08120: Need to create SYS.IND_ONLINE$ table in order to (re)build index
Cause: Alter index Build/Rebuild online require existing of SYS.IND_ONLINE$ table.
Action: User/DBA needs to create sys.ind_online$ before alter the index /rdbms/admin/catcio.sql contains script to create ind_online$. 解決方法就是運行catcio.sql 創建SYS.IND_ONLINE$表SQL> conn / as sysdba
Connected.
SQL> @D:Oracleora92rdbmsadmincatcio除了掃描方式不同外，rebuild 會阻塞dml語句而rebuild online則不會。rebuild online時系統會產生一個SYS_JOURNAL_xxx的IOT類型的系統臨時日志表，所有rebuild online時索引的變化都記錄在這個表中，當新的索引創建完成后，把這個表的記錄維護到新的索引中去，然后drop掉舊的索引，rebuild online就完成了。 Trackback: http://tb.blog.csdn.net/TrackBack.aspx?PostId=1479533
