Wait events

[bensmail]

How can i locate the wait events?
if i have a wait event, how can i lose it ?
anybody had a docu about this thema?

[pando]

tahiti.oracle.cm, reference guide

not sure what do you mean by "lose" a wait event though

[bensmail]

i mean resolve not lose

[pando]

it depends on what group of events, there are 363 wait evet in 9i so it´s not that easy to say :-0
install statspack, it tells you the top 5 waiting events

[bensmail]

Only the most popular!

[pando]

ok, that just confused me, what events are popular?!?!? it depends on database, site to site

have you tried to read the reference guide yet?

[SANJAY_G]

Originally posted by bensmail
Only the most popular!

I don't think any wait event can be popular ..

[hrishy]

Originally posted by bensmail
Only the most popular!

Hi Ben

just take a statspack of the databse you want to monitor.The statspack would be stored in the database and you will have the top 5 wiat events too..:-).Read the stats pack documentation

- Top 5 Events section:

This section shows the Top 5 timed events that must be considered to focus the tuning efforts. Before Oracle 9.2 this section was called "Top 5 Wait Events". It was renamed in Oracle 9.2 to "Top 5 Timed Events" to include the "CPU Time" based on the 'CPU used by this session'. This information will allow you to determine SQL tuning problems.

For further see the Statspack readme file called $ORACLE_HOME/rdbms/admin/spdoc.txt. These events are particularly useful in determining which sections to view next. For instance if there are fairly high waits on latch free or one of the other latches you might want to examine the latch sections first. On the other hand, if the db file read waits events seem abnormally high, you might want to look at the file io section first.

Top 5 Wait Events
~~~~~~~~~~~~~~~~~ Wait % Total
Event Waits Time (cs) Wt Time
-------------------------------------------- ------------ ------------ -------
db file sequential read 12,131,221 173,910 58.04
db file scattered read 93,310 86,884 29.00
log file sync 18,629 9,033 3.01
log file parallel write 18,559 8,449 2.82
buffer busy waits 304,461 7,958 2.66



Notice that in Oracle 9.2 references are made "Elapsed Time" rather than to "Wait Time". Also the "CPU Time" is included as part of the Top events section.
Top 5 Timed Events
~~~~~~~~~~~~~~~~~~ % Total
Event Waits Time (s) Ela Time
-------------------------------------------- ------------ ----------- --------
log file sync 3,223,927 32,481 64.05
CPU time 7,121 14.04
global cache open x 517,153 3,130 6.17
log file parallel write 985,732 2,613 5.15
KJC: Wait for msg sends to complete 568,061 1,794 3.54
-------------------------------------------------------------

Note that db file scattered and sequential read are generally the top wait events when the instance is tuned well and not OPS/RAC. Wait Events

regards
Hrishy

[stmontgo]

let's vote on popular wait events! yeah!!!!!

http://www.dbasupport.com/forums/sho...threadid=36307

ok, for real though, you can look at this pretty decent article
http://otn.oracle.com/oramag/webcolu...eson_wait.html

steve