materialized view
主要用於預先計算並保存表連接或聚集等耗時較多的操作的結果,這樣,在執行查詢時,就可以避免進行這些耗時的操作,而從快速的得到結果。
使用語法:
CREATE MATERIALIZED VIEW XX
REFRESH [[fast
| complete | force]
[on demand | commit]
[start with date]
[next date]
[with {primary key | rowid}]
]
[ENABLE | DISABLE] QUERY REWRITE
遞歸查詢
start with ...指定查詢的根行
connect by prior... 父行和子行的關係(是以父行爲主)
ORDER SIBLINGS BY ... 同級別排序
例:
create materialized view mv_auth_ycps
refresh force on demand
start with to_date('2013-6-25 01:30:00','yyyy-mm-dd hh24:mi:ss')next sysdate+1
as
select *
from acc_domain
where dtype='domain'
start with parent_id is null
connect by prior id = parent_id
ORDER SIBLINGS BY position;
參考資料:http://www.cnblogs.com/lizhe88/archive/2011/01/23/1942423.html