Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> RE: Stuck Query

RE: Stuck Query

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Mon, 22 Sep 2003 18:24:40 -0800
Message-ID: <F001.005D0BC4.20030922182440@fatcity.com>


Fyi, seconds_in_wait is not incremented by queries of v$session_wait. It is incremented by LGWR approximately every three seconds.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com

Upcoming events:

- Hotsos Clinic 101 in Sydney
- Hotsos Symposium 2004, March 7-10 Dallas
- Visit www.hotsos.com for schedule details...


-----Original Message-----
MacGregor, Ian A.
Sent: Monday, September 22, 2003 6:40 PM To: Multiple recipients of list ORACLE-L

Good catch. It was showing Waited Known Time, and the seconds_in_wait kept increasing. I was fooled by the latter being incremented each time v$session_event was queried. I did run a trace on it to track the waits, but had to kill the session. I've never gotten dbms_system session traces to work. They never return anything even on newly rebooted machines.

Ian MacGregor

-----Original Message-----
Sent: Saturday, September 20, 2003 4:05 AM To: Multiple recipients of list ORACLE-L

Hi!

How do you verify that your session is still waiting on sequential read?
>From v$session_event? Is the status column saying WAITING there? (if it
says WAITED%, then your CPU is doing something else already, and this record in session wait just shows the last wait).

Tanel.
----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Saturday, September 20, 2003 12:54 AM

> SQL> describe chanarch_nlc.archive_wave_i
> Name Null? Type
> ----------------------------------------- --------
> ----------------------



> PV_ID NUMBER(38)
> TIMESTAMP DATE
> NANOSECS NUMBER(9)
> STAT NUMBER(8)
> SEVR NUMBER(8)
> OSTAT NUMBER(16)
> VALUE

CHANARCH_NLC.INT_VALUES
>
> SQL> describe chanarch_nlc.arch_wave_i
> Name Null? Type
> ----------------------------------------- --------
> ----------------------


> PV_ID NUMBER(38)
> TIMESTAMP DATE
> NANOSECS NUMBER(9)
> STAT NUMBER(8)
> SEVR NUMBER(8)
> OSTAT NUMBER(16)
> VALUE

CHANARCH_NLC.INT_VALUES
>
>
>
>
> SQL> describe chanarch_nlc.int_values
> chanarch_nlc.int_values VARRAY(16384) OF NUMBER(38)
>
> Select * from chanarch_nlc.arch_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> ORDER BY TIMESTAMP, NANOSECONDS /
>
> Returns 1 row plus the associated varray data in one second
>
> Select * from chanarch_nlc.archive_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> ORDER BY TIMESTAMP, NANOSECONDS
>
> Returns 0 rows in about a second
>
> Select * from chanarch_nlc.arch_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> Union all Select * from chanarch_nlc.archive_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
>
> Returns a single row with the varray data in a second
>
> However
>
> Select * from chanarch_nlc.arch_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> Union all Select * from chanarch_nlc.archive_wave_i
> Where pv_id = 433 and
> Timestamp between '18-SEP-2003:13:48:00' AND '18-SEP-2003:13:49:00'
> Order by 2,3
>
> Never returns. It waits forever on a sequential dbfile read event of
> one

the files used by the lob segment which contains the varray data for the value column of chanarch_nlc.arch_wave_i. Nothing appears to be blocking the session. The query plan is as one would expect.
>
> Similar queries against different tables with the same structure
> proceed

without incident.
>
> Ian MacGregor
> Stanford Linear Accelerator Center
> ian_at_SLAC.Stanford.edu
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> 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.net
-- 
Author: Tanel Poder
  INET: tanel.poder.003_at_mail.ee

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: 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.net
-- 
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 Mon Sep 22 2003 - 21:24:40 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US