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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Autoextend WAIT statistic?
It'll be in the book (Optimizing Oracle Response Time: O'Reilly), still
due out in about June. I'll be working on it pretty much all day, every
day through the end of December. I don't consider myself in the same
league as Lewis/Adams/Kolk/Wood/Holt/Hailey et al. in the V$ domain, but
I do at least have sense enough to ask for their assistance during
research and technical review :).
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic, Dec 9-11 Honolulu
-----Original Message-----
Sent: Wednesday, November 27, 2002 1:59 PM
To: Multiple recipients of list ORACLE-L
I have heard from several sources that the v$ views are not as solid as
they
should be. With all the emphasis on wait and event based tuning, they
should
be more accurate. Has anyone done in-depth research on the collection
methods and accuracy of the x$ and v$ structures? Sounds like a project
for
some of the gurus on the list... <HINT, HINT>
-----Original Message-----
Sent: Tuesday, November 26, 2002 8:25 PM
To: Multiple recipients of list ORACLE-L
As much as the v$"wait" views are touted they do have problems. First,
I
believe they are only updated every 3 seconds and can miss events.
Second,
examine enough samplings from the tables and you'll discover bizarre
data.
Events which managed to wait say 50 seconds in a single sampling period
when
the sampling rate was 5 Hz. On the other hand, one may see events which
are
continuous over many samplings, but their wait times are not
incremented.
If you really want to know what's going on there's no substitute for a
10046
trace.
N.B., I am not stating the v$"wait" statistics tables are useless just
that
they have their shortcomings.
Ian MacGregor
Stanford Linear Accelerator Center
ian_at_SLAC.Stanford.edu
-----Original Message-----
Sent: Tuesday, November 26, 2002 3:26 PM
To: Multiple recipients of list ORACLE-L
Dennis,
I did some quick & dirty testing by creating a very small(10M)
datafile with a large(2000m) autoextend clause. On the insert, the
session
was waiting on 'file open' for most of the time. When I did a rollback
and
reinserted the data, there were no waits (that I saw) on file open.
Interestingly, this wait event does not appear to be accurately tracked in v$session_event. In v$session_wait the seconds in wait (last trapped) was 132. In v$session_event, it shows 0. Okay, gurus, why? Am I missing something in this?
select * from v$session_wait where sid = 14
SID SEQ# EVENT
---------- ----------
SID EVENT TOTAL_WAITS TOTAL_TIMEOUTS
TIME_WAITED AVERAGE_WAIT MAX_WAIT
---------- ------------------------------ ----------- --------------
----------- ------------ ----------
14 rdbms ipc reply 4 1
210 52.5 205
14 control file sequential read 18 0
16 .888888889 15
14 local write wait 1 0
0 0 0
14 log buffer space 72 0
1242 17.25 82
14 log file switch completion 6 0
250 41.6666667 72
14 log file sync 4 0
61 15.25 28
14 db file sequential read 7 0
1 .142857143 1
14 db file scattered read 164 0
152 .926829268 5
14 db file single write 2 0
1 .5 1
14 file identify 4 0
0 0 0
14 file open 6 0
0 0 0
14 SQL*Net message to client 41 0
0 0 0
14 SQL*Net message from client 40 0
67829 1695.725 19952
Dan Fink
-----Original Message-----
Sent: Tuesday, November 26, 2002 2:30 PM
To: Multiple recipients of list ORACLE-L
Oracle says that when a file autoextends, there is a slight delay. Does
anyone know which Oracle WAIT statistic that would appear under?
We have been using autoextend on OLTP production tables for awhile
now,
and the results have been satisfactory. This is an ERP system, so the
critical performance time is at month-end. Some of the developers are
concerned that table autoextending may slow batch programs, and
suggesting
that I should determine which tables are likely to autoextend during
month-end and add storage beforehand. I would like to ensure that I am
fixing a real problem (short on time, like most of you), so I am
wondering
if autoextend was causing a delay, what wait statistic would it show up
under. Any ideas?
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: DENNIS WILLIAMS INET: DWILLIAMS_at_LIFETOUCH.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.com -- Author: Fink, Dan INET: Dan.Fink_at_mdx.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.com -- Author: MacGregor, Ian A. INET: ian_at_SLAC.Stanford.EDU 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.com -- Author: Fink, Dan INET: Dan.Fink_at_mdx.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.com -- Author: Cary Millsap INET: cary.millsap_at_hotsos.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 Nov 27 2002 - 14:54:26 CST
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