降低log file parallel write等待的方法有哪些
发布网友
发布时间：2022-04-12 14:24
共2个回答
懂视网
时间：2022-04-12 18:45
SQL SELECT * FROM v$version;
BANNER
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Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Prod PL/SQL Release 10.2.0.3.0
- Production SQL select name,parameter1,paramet
SQL> SELECT * FROM v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0
- ProdPL/SQL Release 10.2.0.3.0 - Production
SQL>SELECT name,parameter1,parameter2,parameter3,wait_class from v$event_name
2 where name in ('free buffer waits','db file parallel write','write complete waits');
NAME
PARAMETER1 PARAMETER2 PARAMETER3 WAIT_CLASS
------------------------- ---------- ---------- ---------- ------------------------------
free buffer waits
file#
block#
set-id#
Configurationwrite complete waits
file#
block#
Configurationdb file parallel write
requests interrupt timeout System I/O
在Oracle 10g中，db file parallel write 被归属为系统I/0等待类，如果你检查到了系统出现了大量的
db file parallel write事件，表明你的I/O有问题。这时你可以检查
db file parallel write ，write complete waits，free buffer waits的平均等待时间
SQL> select event,time_waited,average_wait from v$system_event where event in
2 ('db file parallel write','write complete waits','free buffer waits');
EVENT
TIME_WAITED AVERAGE_WAIT
---------------------------------------------------------------- ----------- ------------
db file parallel write 284 .67我这里由于是测试机器，没有出现 write complete waits,free buffer waits 等待事件
AVERAGE_WAIT的值应该小于1(百分之一秒)，如果AVERAGE_WAIT大于10（十分之一秒）,表明非常缓慢的I/O，出现了db file parallel write 时常也会伴随write complete waits等待，如果是非常繁忙的OLTP系统，还可能出现free buffer waits，因为缓慢的I/0势必影响前台进程。db file parallel write只属于DBWR进程独有，不要被名字迷惑了，不要误解为该事件与并行DML有关。
热心网友
时间：2022-04-12 15:53
