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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Horrendous Execution Plan from CBO
I'm going along with John. Try the hash join.
CBO was less mature in v7, so it may need a little 'help' to get the plan you want. Such as a 'hash' hint, or the use_nl hint if you don't use the hash.
Jared
"Stahlke, Mark" <mstahlke_at_denvernewspaperagency.com>
Sent by: root_at_fatcity.com
06/07/2002 03:43 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
cc:
Subject: RE: Horrendous Execution Plan from CBO
Thanks for the quick responses.
I analyzed both tables immediately before I started testing.
The USE_MERGE hint gives me the same execution plan I get without hints.
Mark Stahlke
Oracle DuhBA
Denver Newspaper Agency
-----Original Message-----
From: Jared.Still_at_radisys.com
[SMTP:Jared.Still_at_radisys.com]
Sent: Friday, June 07, 2002 3:29 PM
To: ORACLE-L_at_fatcity.com
Cc: mstahlke_at_denvernewspaperagency.com
Subject: Re: Horrendous Execution Plan
from CBO
When were statistics last generated?
Any significant DML since then?
Jared
"Stahlke, Mark" <mstahlke_at_denvernewspaperagency.com>
Sent by: root_at_fatcity.com
06/07/2002 02:51 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L
<ORACLE-L_at_fatcity.com>
cc:
Subject: Horrendous Execution Plan from
CBO
Greetings,
One of our developers came to me with a fairly simple
query that
faster when she uses the RBO. I looked at the execution
plans
both the RBO and CBO and the CBO's plan is horrible. I
was able to
reasonable plan from the CBO using a USE_NL hint.
Do any of you SQL tuning gurus have any suggestions? I've
listed all
gory details below.
Thanks,
Mark Stahlke
Oracle DuhBA
Denver Newspaper Agency
The Gory Details:
Background:
Oracle 7.3.4 (I know, I know). PUB has 531324 rows. CNR
has 601007
Both tables analyzed.
The Query:
1 SELECT
2 c.acct_key,
3 c.pub,
4 c.ref_nbr,
5 c.sls_nbr_1 cnr_sls_nbr,
6 p.sls_eff_iss_1,
7 p.sls_nbr_1_1,
8 p.sls_nbr_1_2,
9 p.sls_eff_iss_2,
10 p.sls_nbr_2_1,
11 p.sls_nbr_2_2,
12 p.sls_eff_iss_3,
13 p.sls_nbr_3_1,
14 p.sls_nbr_3_2
15 FROM cnr c, pub p
16 WHERE c.acct_key = p.acct_key
17* AND c.pub = p.pub
Plan and stats without hints:
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=28838
Card=597847
tes=100438296)
1 0 MERGE JOIN (Cost=28838 Card=597847
Bytes=100438296)
2 1 SORT (JOIN)
3 2 TABLE ACCESS (FULL) OF 'PUB' (Cost=841
Card=529489
es=55066856)
4 1 SORT (JOIN)
5 4 TABLE ACCESS (FULL) OF 'CNR' (Cost=2195
Card=598749
tes=38319936)
Statistics
----------------------------------------------------------
365 recursive calls
12740 db block gets
53167 consistent gets
96684 physical reads
4956 redo size
45285104 bytes sent via SQL*Net to client
441377 bytes received via SQL*Net from client
40070 SQL*Net roundtrips to/from client
0 sorts (memory)
2 sorts (disk)
601007 rows processed
Plan and stats with /*+ RULE */
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=HINT: RULE
1 0 NESTED LOOPS
2 1 TABLE ACCESS (FULL) OF 'PUB'
3 1 TABLE ACCESS (BY ROWID) OF 'CNR'
4 3 INDEX (RANGE SCAN) OF 'PK_CNR' (UNIQUE)
Statistics
----------------------------------------------------------
0 recursive calls
4 db block gets
2828280 consistent gets
69635 physical reads
0 redo size
45285104 bytes sent via SQL*Net to client
441389 bytes received via SQL*Net from client
40070 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
601007 rows processed
Plan and stats with /*+ USE_NL(c p) */
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1204217
Card=601007
Bytes=100969176)
1 0 NESTED LOOPS (Cost=1204217 Card=601007
Bytes=100969176)
2 1 TABLE ACCESS (FULL) OF 'CNR' (Cost=2203
Card=601007
s=38464448)
3 1 TABLE ACCESS (BY ROWID) OF 'PUB' (Cost=844
Card=531324
ytes=55257696)
4 3 INDEX (UNIQUE SCAN) OF 'PK_PUB' (UNIQUE)
Statistics
----------------------------------------------------------
0 recursive calls
4 db block gets
3062526 consistent gets
69490 physical reads
0 redo size
45285104 bytes sent via SQL*Net to client
441396 bytes received via SQL*Net from client
40070 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
601007 rows processed
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Stahlke, Mark
INET: mstahlke_at_denvernewspaperagency.com
Fat City Network Services -- (858) 538-5051 FAX:
(858) 538-5051
San Diego, California -- Public Internet access /
Mailing
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stahlke, Mark INET: mstahlke_at_denvernewspaperagency.com 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: 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: INET: Jared.Still_at_radisys.com 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: 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 Fri Jun 07 2002 - 18:31:07 CDT
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