如何在awr里面查看 log file sync是否是由用户commit太多造成

来源：互联网发布：科多大数据上海编辑：程序博客网时间：2024/05/22 14:34

根据Tanel Põder:

Reasons for log file sync waits

• Commits wait for log file sync by default

• User commits

• There’s an user commits statistic in v$sesstat

• DDL（如,create table ，但是drop table不会有，可以观察 v$sysstat里面的user commits，或者10046 trace里面的等待事件）

• Resulting recursive transactions commit

• Recursive data dictionary DML

• Rollbacks wait too!

• User rollbacks

• User/application issued a rollback command

• Transaction rollbacks

• We had an internal rollback (because of some failure)

• Space allocation/ASSM problems, cancelled queries, killed sessions

在v$sysstat视图里面的表现就是

user commits

user rollbacks

transaction rollbacks

如果这样推断，那么在awr里面可以观察这三个统计信息的数值来做参开是否由于用户原因造成log file sync waits

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