Oracle 中时间函数sessiontmezone 和 dbtimezone 的区别
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发布时间:2022-05-01 12:49
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懂视网
时间:2022-05-01 17:10
(4)等待事件分两类: 非空闲 + 空闲等待事件(IDLE)
大部分空闲等待事件 都是客户端相关的消息传输事件
大量idel等待事件造成的性能问题,极有可能是应用服务器本身问题,或者网络问题,因为cpu 都空闲了。
查看下数据库的等待事件数据
select event,time_waited,average_wait from v$system_event
where event not in (
‘pmon time‘,
‘smon timer‘,
‘rdbms ipc message‘,
‘parallel dequeue wait‘,
‘virtual circuit‘,
‘SQL*Net message from client‘,
‘client message‘,
‘NULL event‘
)
order by time_waited desc;
结果如下:
EVENT TIME_WAITED AVERAGE_WAIT
---------------------------------------------------------------- ----------- ------------
DIAG idle wait 935522655 100.09
jobq slave wait 497321787 50.08
shared server idle wait 467876357 3000.92
Streams AQ: qmn coordinator idle wait 467875026 1400.44
Streams AQ: qmn slave idle wait 467873982 2737.96
dispatcher timer 467872026 6000.98
pmon timer 467819350 264.77
Space Manager: slave idle wait 467784915 499.1
Streams AQ: waiting for time management or cleanup tasks 464980103 1690836.74
VKRM Idle 169919651 3146660.21
os thread startup 290703 1.59
control file parallel write 126076 .08
log file parallel write 100734 .03
log file sync 61970 .08
db file async I/O submit 34403 .03
library cache lock 22077 959.85
PL/SQL lock timer 12407 98.47
control file sequential read 6042 0
ADR block file read 1845 .11
auto-sqltune: wait graph update 1500 250.02
Disk file operations I/O 1482 0
direct path sync 778 1.05
log file switch completion 537 .81
control file heartbeat 400 400
reliable message 392 .05
SQL*Net message to client 375 0
db file sequential read 364 .01
resmgr:internal state change 342 10.06
class slave wait 327 .01
asynch descriptor resize 326 0
switch logfile command 227 56.68
rdbms ipc reply 209 .06
enq: CR - block range reuse ckpt 134 .07
LGWR wait for redo copy 112 0
undo segment extension 110 .75
ADR block file write 91 .01
db file scattered read 85 .01
log file single write 55 .04
JS coord start wait 50 50.02
enq: PR - contention 36 1.17
db file single write 35 .02
enq: RO - fast object reuse 27 .01
latch: shared pool 25 .03
direct path write temp 24 .01
latch free 19 .15
Data file init write 15 .21
这是oracle性能调优的基础。
本文出自 “梁小明的博客” 博客,请务必保留此出处http://7038006.blog.51cto.com/7028006/1863399
浅谈oracle数据库dbtime
标签:浅谈oracle数据库dbtime
热心网友
时间:2022-05-01 14:18
DBTIMEZONE:是数据库服务器所在的时区。
SESSIONTIMEZONE :是你的会话的时区。
例如:数据库服务器是放在英国(+00:00时区),而你在中国(+08:00)访问数据库,则SESSIONTIMEZONE 就是+08:00,DBTIMEZONE就是+00:00
热心网友
时间:2022-05-01 15:36
db是数据库的,session是针对当前会话的,因为时区在会话级可以改变