请教：关于db file sequential read 等待的问题

com_dlj

原帖由 Yong Huang 于 2008-2-20 12:52 发表


Did you do anything else immediately after you restarted the database? Try flushing buffer cache (alter system flush buffer_cache) before you enable SQL trace and select from the table.

Yong Huang

是本机的测试库,
重启数据库就是为干净的清除buffer_cache 中的数据;重启后,没有其他连接做操作;alter system flush buffer_cache 是10g 后才可以使用的吧

Yong Huang

原帖由 com_dlj 于 2008-2-20 01:44 发表

是本机的测试库,
重启数据库就是为干净的清除buffer_cache 中的数据;重启后,没有其他连接做操作;alter system flush buffer_cache 是10g 后才可以使用的吧

In 9i, you can
ALTER SYSTEM SET EVENTS 'immediate trace name flush_cache';

My test shows that once you flush buffer cache, you'll see the wait on reading the segment header.

Yong Huang

com_dlj

原帖由 Yong Huang 于 2008-2-21 02:21 发表


In 9i, you can
ALTER SYSTEM SET EVENTS 'immediate trace name flush_cache';

My test shows that once you flush buffer cache, you'll see the wait on reading the segment header.

Yong Huang

多谢,这次正确了.但还不明白,为何数据库重启后,看不到段头的db file sequential read