The result depends on the number of sessions. If you have
session A waiting for a 'enqueue lock' for 10 minutes and session
B waiting for the same lock as session A for another 10 minutes,
then the recorded time is 20 minutes, despite the fact that sessions
are waiting concurrently. If you have, say, 500 concurrent sessions,
the numbers will be exorbitant.
V$SYSTEM_EVENT is a summary table and not very useful at that. Your
query gives you the most important thing:the percentages. The
percentages tell you that I/O related events ('scattered read' for
table scans and 'sequential read' for index scans) are not taking too
much time, relative to the other events. In other words, you found
another way of calculating BHCR and have significantly advanced
something that one of the recent books calls "method C".
On 01/21/2004 11:44:25 AM, "Shrake, Jolene" wrote:
>
> These results don't seem possible.
>
> I run the following query:
> select ((vse.time_waited/100)/60) time_waited,
> ((vse.time_waited/vse1.total_time)*100) p_time_waited,
> vse.event
> from v$system_event vse, (select sum(time_waited) total_time from
> v$system_event) vse1
> where ((vse.time_waited/100)/60) >= .1
> and vse.event not in ('SQL*Net message from client','rdbms ipc
> message','pmon timer','smon timer')
> order by 2 desc
> /
>
> The system is 8.1.7.4 running Oracle Applications 11.5.7 on HPUX
> 11.11.
>
> The database has been up since Sunday night after the cold backup.
>
> These results seem too large. Any thoughts?
>
> Time Waited % Time
> (min) Waited Wait Event
> ------------ ------- ----------------------------
> 50,771.54 2.30 db file sequential read
> 19,129.29 .86 db file scattered read
> 15,735.79 .71 latch free
> 15,321.68 .69 io done
> 15,248.34 .69 log file sync
> 14,866.87 .67 buffer busy waits
> 14,718.91 .67 log file parallel write
>
> Thanks for your help,
> Jolene
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Shrake, Jolene
> INET: JEShrake_at_Pella.com
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
> (or the name of mailing list you want to be removed from). You may
> also send the HELP command for other information (like subscribing).
>
--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Mladen Gogala
INET: mladen_at_wangtrading.com
Fat City Network Services -- 858-538-5051 http://www.fatcity.com
San Diego, California -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
Received on Wed Jan 21 2004 - 12:39:29 CST
