Re: Explain THIS plan.
Try 'select /*+ ORDERED */'
hth
connor
--- Kirsch, Walter J (Northrop Grumman)
[EMAIL PROTECTED] wrote:
2-cpu, 220mhz, 32-bit HPUX 11.0. Oracle 8.1.7.0.0
Could someone explain what's going on here?
This SQL takes no time at all :
select
substr(username , 1, 12) User
, substr(lock_type, 1, 18) Lock Type
, substr(mode_held, 1, 18) Mode Held
from sys.dba_lock a
, v$sessionb
where /*lock_type not in ('Media Recovery','Redo
Thread')
and*/ a.session_id = b.sid;
with explain plan:
SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1
Bytes=148)
NESTED LOOPS (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=60 Card=1 Bytes=141)
NESTED LOOPS (Cost=20 Card=1 Bytes=107)
FIXED TABLE (FULL) OF X$KSUSE (Cost=10
Card=1 Bytes=30)
FIXED TABLE (FIXED INDEX #1) OF X$KSUSE
(Cost=10 Card=1
Bytes=77)
VIEW OF GV$_LOCK
UNION-ALL
VIEW OF GV$_LOCK1 (Cost=20 Card=2
Bytes=162)
UNION-ALL
FIXED TABLE (FULL) OF X$KDNSSF
(Cost=10 Card=1
Bytes=94)
FIXED TABLE (FULL) OF X$KSQEQ
(Cost=10 Card=1
Bytes=94)
FIXED TABLE (FULL) OF X$KTADM (Cost=10
Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTCXB (Cost=10
Card=1 Bytes=94)
FIXED TABLE (FIXED INDEX #1) OF X$KSQRS
(Cost=10 Card=100
Bytes=700)
whereas an uncommented predicate consumes 40 minutes
of CPU (sez TOP) with
this explain plan:
SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1
Bytes=148)
NESTED LOOPS (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=30 Card=1 Bytes=114)
MERGE JOIN (CARTESIAN) (Cost=20 Card=1
Bytes=37)
FIXED TABLE (FULL) OF X$KSUSE (Cost=10
Card=1 Bytes=30)
SORT (JOIN) (Cost=10 Card=1 Bytes=7)
FIXED TABLE (FULL) OF X$KSQRS (Cost=10
Card=1 Bytes=7)
FIXED TABLE (FIXED INDEX #1) OF X$KSUSE
(Cost=10 Card=1
Bytes=77)
VIEW OF GV$_LOCK
UNION-ALL
VIEW OF GV$_LOCK1 (Cost=20 Card=2
Bytes=162)
UNION-ALL
FIXED TABLE (FULL) OF X$KDNSSF (Cost=10
Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KSQEQ (Cost=10
Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTADM (Cost=10
Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTCXB (Cost=10
Card=1 Bytes=94)
If it jams, force it. If it breaks, it needed
replacing anyway. --John F
Duval
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Re: Explain THIS plan.
Kirsch, Walter J (Northrop Grumman) wrote:
2-cpu, 220mhz, 32-bit HPUX 11.0. Oracle 8.1.7.0.0
Could someone explain what's going on here?
This SQL takes no time at all :
select
substr(username , 1, 12) User
, substr(lock_type, 1, 18) Lock Type
, substr(mode_held, 1, 18) Mode Held
from sys.dba_lock a
, v$sessionb
where /*lock_type not in ('Media Recovery','Redo Thread')
and*/ a.session_id = b.sid;
with explain plan:
SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=60 Card=1 Bytes=141)
NESTED LOOPS (Cost=20 Card=1 Bytes=107)
FIXED TABLE (FULL) OF X$KSUSE (Cost=10 Card=1 Bytes=30)
FIXED TABLE (FIXED INDEX #1) OF X$KSUSE (Cost=10 Card=1
Bytes=77)
VIEW OF GV$_LOCK
UNION-ALL
VIEW OF GV$_LOCK1 (Cost=20 Card=2 Bytes=162)
UNION-ALL
FIXED TABLE (FULL) OF X$KDNSSF (Cost=10 Card=1
Bytes=94)
FIXED TABLE (FULL) OF X$KSQEQ (Cost=10 Card=1
Bytes=94)
FIXED TABLE (FULL) OF X$KTADM (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTCXB (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FIXED INDEX #1) OF X$KSQRS (Cost=10 Card=100
Bytes=700)
whereas an uncommented predicate consumes 40 minutes of CPU (sez TOP) with
this explain plan:
SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=30 Card=1 Bytes=114)
MERGE JOIN (CARTESIAN) (Cost=20 Card=1 Bytes=37)
FIXED TABLE (FULL) OF X$KSUSE (Cost=10 Card=1 Bytes=30)
SORT (JOIN) (Cost=10 Card=1 Bytes=7)
FIXED TABLE (FULL) OF X$KSQRS (Cost=10 Card=1 Bytes=7)
FIXED TABLE (FIXED INDEX #1) OF X$KSUSE (Cost=10 Card=1
Bytes=77)
VIEW OF GV$_LOCK
UNION-ALL
VIEW OF GV$_LOCK1 (Cost=20 Card=2 Bytes=162)
UNION-ALL
FIXED TABLE (FULL) OF X$KDNSSF (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KSQEQ (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTADM (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTCXB (Cost=10 Card=1 Bytes=94)
If it jams, force it. If it breaks, it needed replacing anyway. --John F
Duval
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Kirsch, Walter J (Northrop Grumman)
INET: [EMAIL PROTECTED]
Walter,
Keep in mind that X$ tables (which underlay the V$ views) are
relational representations of memory structures ''SGA-as-tables'). In
two words : no statistics. In one acronym : RBO. NOT IN is to the RBO a
strong 'full scan' signal. Add to this the absence of any join condition
on 'a' and 'b' (noticed the cartesian merge ?) and anything can happen.
--
Regards,
Stephane Faroult
Oriole Software
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Stephane Faroult
INET: [EMAIL PROTECTED]
Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051
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RE: Explain THIS plan. SOLVED
select /*+ rule */ ...
cut the execution time to nil.
Thanks to Charlie Mengler for help and Tim Gorman for a note in his i.sql
that solved the problem.
-Original Message-
[mailto:[EMAIL PROTECTED]]
Sent: Tuesday, May 14, 2002 3:09 PM
To: Multiple recipients of list ORACLE-L
2-cpu, 220mhz, 32-bit HPUX 11.0. Oracle 8.1.7.0.0
Could someone explain what's going on here?
This SQL takes no time at all :
select
substr(username , 1, 12) User
, substr(lock_type, 1, 18) Lock Type
, substr(mode_held, 1, 18) Mode Held
from sys.dba_lock a
, v$sessionb
where /*lock_type not in ('Media Recovery','Redo Thread')
and*/ a.session_id = b.sid;
with explain plan:
SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=60 Card=1 Bytes=141)
NESTED LOOPS (Cost=20 Card=1 Bytes=107)
FIXED TABLE (FULL) OF X$KSUSE (Cost=10 Card=1 Bytes=30)
FIXED TABLE (FIXED INDEX #1) OF X$KSUSE (Cost=10 Card=1
Bytes=77)
VIEW OF GV$_LOCK
UNION-ALL
VIEW OF GV$_LOCK1 (Cost=20 Card=2 Bytes=162)
UNION-ALL
FIXED TABLE (FULL) OF X$KDNSSF (Cost=10 Card=1
Bytes=94)
FIXED TABLE (FULL) OF X$KSQEQ (Cost=10 Card=1
Bytes=94)
FIXED TABLE (FULL) OF X$KTADM (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTCXB (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FIXED INDEX #1) OF X$KSQRS (Cost=10 Card=100
Bytes=700)
whereas an uncommented predicate consumes 40 minutes of CPU (sez TOP) with
this explain plan:
SELECT STATEMENT Optimizer=CHOOSE (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=70 Card=1 Bytes=148)
NESTED LOOPS (Cost=30 Card=1 Bytes=114)
MERGE JOIN (CARTESIAN) (Cost=20 Card=1 Bytes=37)
FIXED TABLE (FULL) OF X$KSUSE (Cost=10 Card=1 Bytes=30)
SORT (JOIN) (Cost=10 Card=1 Bytes=7)
FIXED TABLE (FULL) OF X$KSQRS (Cost=10 Card=1 Bytes=7)
FIXED TABLE (FIXED INDEX #1) OF X$KSUSE (Cost=10 Card=1
Bytes=77)
VIEW OF GV$_LOCK
UNION-ALL
VIEW OF GV$_LOCK1 (Cost=20 Card=2 Bytes=162)
UNION-ALL
FIXED TABLE (FULL) OF X$KDNSSF (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KSQEQ (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTADM (Cost=10 Card=1 Bytes=94)
FIXED TABLE (FULL) OF X$KTCXB (Cost=10 Card=1 Bytes=94)
If it jams, force it. If it breaks, it needed replacing anyway. --John F
Duval
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Kirsch, Walter J (Northrop Grumman)
INET: [EMAIL PROTECTED]
Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051
San Diego, California-- Public Internet access / Mailing Lists
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (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: Kirsch, Walter J (Northrop Grumman)
INET: [EMAIL PROTECTED]
Fat City Network Services-- (858) 538-5051 FAX: (858) 538-5051
San Diego, California-- Public Internet access / Mailing Lists
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (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).
