[20130527]估计redo文件的大小.txt

[20130527]估计redo文件的大小.txt

    oracle一般建议20-30分钟切换一次redo文件.简单的查询计算如下:

参考链接:
http://www.gokhanatil.com/2009/08/optimum-size-of-the-online-redo-log-files.html

        
SELECT
(SELECT ROUND(AVG(BYTES) / 1024 / 1024, 2) FROM V$LOG) AS "Redo size (MB)",
ROUND((20 / AVERAGE_PERIOD) * (SELECT AVG(BYTES)
FROM V$LOG) / 1024 / 1024, 2) AS "Recommended Size (MB)"
FROM (SELECT AVG((NEXT_TIME - FIRST_TIME) * 24 * 60) AS AVERAGE_PERIOD
FROM V$ARCHIVED_LOG
WHERE FIRST_TIME > SYSDATE - 3
AND TO_CHAR(FIRST_TIME, 'HH24:MI') BETWEEN
&START_OF_PEAK_HOURS AND &END_OF_PEAK_HOURS);

--如果换成30分钟,修改红色部分.