oracle oracle物化视图刷新时间
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oracle materialized view refresh time
提问by shaunf
anyone able to tell me how often a materialized view is set to refresh with the following setting plz?
谁能告诉我使用以下设置刷新物化视图的频率？
REFRESH FORCE ON DEMAND START WITH sysdate+0 NEXT (round(sysdate) + 1/24) + 1
REFRESH FORCE ON DEMAND START WITH sysdate+0 NEXT (round(sysdate) + 1/24) + 1
i think i read it as every hour but i'm not sure
我想我每小时都读一遍，但我不确定
回答by tuinstoel
SQL> alter session set nls_date_format = 'yyyy-mm-dd :hh24:mi:ss';
Session changed.
SQL> select sysdate from dual;
SYSDATE
--------------------
2008-12-19 :12:18:28
SQL> select (round(sysdate) + 1/24) + 1 from dual;
(ROUND(SYSDATE)+1/24
--------------------
2008-12-21 :01:00:00
回答by Stew S
To answer your first question (will this run once an hour?):
回答你的第一个问题（这会每小时运行一次吗？）：
Nope, this will run once when you create it because of this clause:
不，由于此子句，这将在您创建它时运行一次：
START WITH sysdate+0
Personally, I think the "+0" is extraneous, as now is now.
就个人而言，我认为“+0”是无关紧要的，就像现在一样。
Then it will run tomorrow at 1 a.m., because of the following clause:
然后它将在明天凌晨 1 点运行，因为以下子句：
NEXT (round(sysdate) + 1/24) + 1
The "1/24" part calculates when 1 a.m. is, since Oracle dates are actually stored as numbers, with the decimal part indicating hours, minutes, etc. The syntax is just fine.
“1/24”部分计算凌晨 1 点，因为 Oracle 日期实际上存储为数字，小数部分表示小时、分钟等。语法很好。
回答by David Aldridge
I'm not 100% sure that it's legal in a materialized view scheduling statement, but you might like to try the (arguably) more intuitive INTERVAL specification:
我不是 100% 确定它在物化视图调度语句中是合法的，但您可能想尝试（可以说）更直观的 INTERVAL 规范：
round(sysdate) + interval '1 1' day to hour
Other examples here: http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements003.htm#SQLRF00221
此处的其他示例：http: //download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements003.htm#SQLRF00221
回答by Nadi E Musleh
i think using
我认为使用
NEXT (trunc(sysdate) + 1/24) + 1
is more accurate
更准确
