SQLServer中使用索引视图(物化视图)
时间:2014-05-12 00:12:34
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物化视图:以前用的普通的视图,普通视图就是一段逻辑语句,对性能没有任何的提升,也不能创建索引,而物化视图会把视图里查询出来的数据在数据库上建立快照,它和物理表一样,可以创建 索引,主键约束等等,性能会有质的提升,但是其有缺点,会占用,可以设置它定时自动更新一次,也可以手动更新,当然也是可以设置及时更新的,但是会拉慢基表的增删改查操作,在这里我只讲思路,具体的话大家可以自己去研究。
--创建物化视图,每天晚上22:00:00自动更新 create materialized view
VM_PSNPERSONINFO refresh force
on demand start with
sysdate next
to_date( concat( to_char( sysdate+1, ‘dd-mm-yyyy‘ ), ‘ 22:00:00‘ ), ‘dd-mm-yyyy hh24:mi:ss‘ ) as SELECT dt.personid, c.employeeid,d.unitcode,d.unitname,d.label, dt.unitid,dt.startdate,dt.enddate FROM
( SELECT
DISTINCT b.personnelid personid,SUBSTR (a.effectdate, 1, 10) startdate, MIN
( CASE WHEN a.effectdate < b.effectdate THEN
b.effectdate ELSE
N ‘9999-99-99‘
END ) AS
enddate, MIN
(a.adjustresult) unitid FROM
psnadjust a LEFT
JOIN psnadjust b ON
a.personnelid = b.personnelid WHERE
a.adjusttype = ‘2‘
AND b.adjusttype = ‘2‘ GROUP
BY b.personnelid, a.effectdate ) dt INNER
JOIN psnaccessioninfo c ON
c.personid = dt.personid INNER
JOIN orgstdstruct d ON
d.unitid = dt.unitid ORDER BY employeeid, unitcode, startdate; |
http://www.cnblogs.com/zhxhdean/archive/2011/05/16/2047795.html
http://blog.163.com/ybhjj2005@126/blog/static/561082842007235010598/
http://www.cnblogs.com/liuzhendong/archive/2011/10/10/2205744.html
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