带你快速了解wait等待事件及其处理方法

1、db file sequential read

调整SQL,增加buffer cache,加快磁盘读写速度

2、log file sync

减少事务提交，将redo文件存放于高速硬盘

3、db file scattered read

FTS-调整SQL,增加索引，加快磁盘读写速度

4、latch free – need p1,p2,p3

5、enqueue – need p1,p2,p3 and SQL

6、SQL*Net more data from client

减少数据传输，网络优化

7、direct path read

排序问题，调整IO或者减少排序

8、direct path write

直接路径访问问题，加快磁盘读写速度

9、buffer busy waits – need p1,p2,p3 and SQL

10.SQL*Net more data to client

减少数据传输，网络优化

11.log buffer space

加大log buffer

12.log file switch completion

加大log文件尺寸大小

13.library cache pin

减少相同游标的并发解析，比如绑定变量

14.SQL*Net break/reset to client

检查SQL语句是否出错

15.file open

减少log文件打开

16.free buffer waits

增加buffer cache size

17.db file parallel read

调整SQL，优化IO，加大buffer cache

18.write complete waits

增加buffer cache ，或者优化DBWR

20.library cache lock

避免同一时间进行硬解析

21.SQL*Net more data from dblink

减少数据传输，网络优化

22.log file switch (checkpoint incomplete)

增加log文件，或者调整加大log文件的大小

23.library cache load lock

避免同一时间cursor进行硬解析

24.row cache lock

need p1

25.local write wait

truncates / reduce cache size

降低cache size

26.sort segment request

SMON busy, process rollback problem

SMON进出繁忙，rollback问题

27.process startup

在MTS情况下，增加init.ORA文件中min servers and dispatchers参数

28.file identify

降低CHECKPOINTS，保持文件打开

29.pipe put

加快pipe管道读

30.switch logfile command

避免频繁进行log切换

31.SQL*Net break/reset to dblink

检查sql是否有误

32.log file switch (archiving needed)

归档空间不足

33.direct path write (lob)

优化IO，减少lob读写

34.undo segment extension

Use UNDO or with RBS, increase RBS size, avoid OPTIMAL

35.undo segment tx slot

Use UNDO, increae # of RBS segs