Dynamic sampling coming in the NOTE section of the explain plan.

Hi i am using 10.2.0.4.0 of oracle.
During findout the autotrace plan of one of the sql i am getting a note as '- dynamic sampling used for this statement'. So wanted to know, whether this will affect the path of execution?
below is the plan .
| Id | Operation                                 | Name                       | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads | OMem | 1Mem |
|
|   1 | SORT ORDER BY                            |                            |      1 |      1 |   8 |00:00:03.77 |    8919 |    188 | 4096 | 4096 | 40
|   2 |   NESTED LOOPS                            |                            |      1 |      1 |   8 |00:00:00.07 |    8919 |    188 |          |       |
|
|   3 |    NESTED LOOPS                           |                            |      1 |      1 |   8 |00:00:00.06 |    8885 |    188 |          |       |
|
|   4 |     NESTED LOOPS OUTER                    |                            |      1 |      1 |   8 |00:00:00.06 |    8859 |    188 |          |       |
|
|   5 |      NESTED LOOPS OUTER                   |                            |      1 |      1 |   8 |00:00:00.06 |    8841 |    188 |          |       |
|
|   6 |       NESTED LOOPS                        |                            |      1 |      1 |   8 |00:00:00.06 |    8839 |    188 |          |       |
|
|   7 |        NESTED LOOPS                       |                            |      1 |     42 |   8 |00:00:00.01 |      51 | 6 |       |       |
|   8 |         PARTITION LIST ALL                |                            |      1 |   2716 |   8 |00:00:00.01 |      25 | 6 |       |       |
|   9 |          TABLE ACCESS BY LOCAL INDEX ROWID| a                          |     12 |   2716 |   8 |00:00:00.10 |      25 | 6 |       |       |
|* 10 |           INDEX RANGE SCAN                | IDX_SPI_GRP                |     12 |   2716 |   8 |00:00:00.10 |      24 | 6 |       |       |
|* 11 |         TABLE ACCESS BY INDEX ROWID       | b                          |      8 |      1 |   8 |00:00:00.01 |      26 | 0 |       |       |
|* 12 |          INDEX RANGE SCAN                 | IDX_XMLONLINEVIEW_VENDORID |      8 |      2 |   8 |00:00:00.01 |      18 | 0 |       |       |
| 13 |        PARTITION RANGE ALL                |                            |      8 |      1 |   8 |00:00:03.67 |    8788 |    182 |          |       |
|
| 14 |         PARTITION HASH ALL                |                            |    424 |      1 |   8 |00:00:03.67 |    8788 |    182 |          |       |
|
|* 15 |          TABLE ACCESS BY LOCAL INDEX ROWID| c                          |   3392 |      1 |   8 |00:00:03.66 |    8788 |    182 |          |       |
|
|* 16 |           INDEX RANGE SCAN                | IDX_UP_INVNUM_DISB         |   3392 |      3 |   8 |00:00:03.55 |    8772 |    177 |          |       |
|
|* 17 |       INDEX UNIQUE SCAN                   | SF_INVDISCOUNT_DISB_P1     |      8 |      1 |   0 |00:00:00.01 |       2 | 0 |       |       |
|* 18 |      INDEX UNIQUE SCAN                    | P_CALCDISCNTPYMNT          |      8 |      1 |   0 |00:00:00.01 |      18 | 0 |       |       |
| 19 |     TABLE ACCESS BY INDEX ROWID           | d                          |      8 |      1 |   8 |00:00:00.01 |      26 | 0 |       |       |
|* 20 |      INDEX UNIQUE SCAN                    | PAYIDENTITY_BASE_PKI       |      8 |      1 |   8 |00:00:00.01 |      18 | 0 |       |       |
| 21 |    TABLE ACCESS BY INDEX ROWID            | e                          |      8 |      1 |   8 |00:00:00.01 |      34 | 0 |       |       |
|* 22 |     INDEX UNIQUE SCAN                     | P_INVOICESUMMARY           |      8 |      1 |   8 |00:00:00.01 |      26 | 0 |       |       |
Note
   - dynamic sampling used for this statementEdited by: 930254 on Jun 5, 2012 4:18 AM

930254 wrote:
Hi i am using 10.2.0.4.0 of oracle.
During findout the autotrace plan of one of the sql i am getting a note as '- dynamic sampling used for this statement'. So wanted to know, whether this will affect the path of execution?
Note
- dynamic sampling used for this statement
It could do - you might get a different sample, which could result in different cardinality estimates, which could mean a different plan, every time you optimize this query.
On the other hand, the sampling may result in cardinality estimates that always look the same and always produce the same plan - and could even match the plan you would get after gather statistics at 100% with histograms everywhere.
Regards
Jonathan Lewis

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Sub Partitioning does not have considerable impact Explain Plan

Hi Guys,
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Hi Dom
Thanks for your reply.
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Below are the output of the Explain Plan and Trace Output -
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> show parameter optimizer;
NAME TYPE VALUE
optimizer_capture_sql_plan_baselines boolean FALSE
optimizer_dynamic_sampling integer 2
optimizer_features_enable string 11.2.0.3
optimizer_index_caching integer 0
optimizer_index_cost_adj integer 100
optimizer_mode string ALL_ROWS
optimizer_secure_view_merging boolean TRUE
optimizer_use_invisible_indexes boolean FALSE
optimizer_use_pending_statistics boolean FALSE
optimizer_use_sql_plan_baselines boolean TRUE
SQL> show parameter db_file_multi;
NAME TYPE VALUE
db_file_multiblock_read_count integer 128
SQL> show parameter cursor_sharing
NAME TYPE VALUE
cursor_sharing string EXACT
SQL> column sname format a20
SQL> column pname foramt 20
SP2-0158: unknown COLUMN option "foramt"
SQL> column pname format a20
SQL> column pval2 format a20
SQL> select
2 sname
3 , pname
4 , pval1
5 ,pval2
6 from sys.aux_stats$;
from sys.aux_stats$
ERROR at line 6:
ORA-00942: table or view does not exist
SQL> explain plan for
select MOBILENUMBER, CLOSING_BAL from GSM_PRR_SUM_NEW a1
where A1.CIRCLE_ID ='KA'
AND a1.LOAD_DTTM BETWEEN '28-MAR-2012' AND '03-APR-2012'
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value: 3032220315
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)
| Time | Pstart| Pstop |
PLAN_TABLE_OUTPUT
| 0 | SELECT STATEMENT | | 41M| 1643M| 548M(100)
|999:59:59 | | |
| 1 | PARTITION LIST SINGLE | | 41M| 1643M| 548M(100)
|999:59:59 | KEY | KEY |
| 2 | PARTITION LIST ITERATOR| | 41M| 1643M| 548M(100)
|999:59:59 | KEY | KEY |
| 3 | TABLE ACCESS FULL | GSM_PRR_SUM_NEW | 41M| 1643M| 548M(100)
|999:59:59 | KEY | KEY |
PLAN_TABLE_OUTPUT
Note
- dynamic sampling used for this statement (level=2)
14 rows selected.
SQL> explain plan for
select MOBILENUMBER, CLOSING_BAL from GSM_PRR_SUM_NEW a1
where A1.CIRCLE_ID ='KA'
AND to_char(a1.LOAD_DTTM) like '%MAR%';
2 3 4
Explained.
SQL> SQL> SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value: 189546713
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| T
ime | Pstart| Pstop |
PLAN_TABLE_OUTPUT
| 0 | SELECT STATEMENT | | 62M| 2521M| 5435M(100)|99
9:59:59 | | |
| 1 | PARTITION LIST SINGLE| | 62M| 2521M| 5435M(100)|99
9:59:59 | KEY | KEY |
| 2 | PARTITION LIST ALL | | 62M| 2521M| 5435M(100)|99
9:59:59 | 1 | 305 |
|* 3 | TABLE ACCESS FULL | GSM_PRR_SUM_NEW | 62M| 2521M| 5435M(100)|99
9:59:59 | KEY | KEY |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
3 - filter(TO_CHAR(INTERNAL_FUNCTION("A1"."LOAD_DTTM")) LIKE '%MAR%')
Note
PLAN_TABLE_OUTPUT
- dynamic sampling used for this statement (level=2)
19 rows selected.
SQL>
SQL> SET AUTOTRACE TRACEONLY ARRAYSIZE 100
SQL> select MOBILENUMBER, CLOSING_BAL from GSM_PRR_SUM_NEW a1
where A1.CIRCLE_ID ='KA'
AND a1.LOAD_DTTM BETWEEN '28-MAR-2012' AND '03-APR-2012' 2 3 ;
49637012 rows selected.
Execution Plan
Plan hash value: 3032220315
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)
| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 41M| 1643M| 546M(100)
|999:59:59 | | |
| 1 | PARTITION LIST SINGLE | | 41M| 1643M| 546M(100)
|999:59:59 | KEY | KEY |
| 2 | PARTITION LIST ITERATOR| | 41M| 1643M| 546M(100)
|999:59:59 | KEY | KEY |
| 3 | TABLE ACCESS FULL | GSM_PRR_SUM_NEW | 41M| 1643M| 546M(100)
|999:59:59 | KEY | KEY |
Note
- dynamic sampling used for this statement (level=2)
Statistics
0 recursive calls
7 db block gets
530220 consistent gets
33636 physical reads
0 redo size
644311477 bytes sent via SQL*Net to client
5460594 bytes received via SQL*Net from client
496372 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
49637012 rows processed
SQL> SET AUTOTRACE TRACEONLY ARRAYSIZE 100
SQL> select MOBILENUMBER, CLOSING_BAL from GSM_PRR_SUM_NEW a1
where A1.CIRCLE_ID ='KA'
AND to_char(a1.LOAD_DTTM) like '%MAR%' 2 3
4 ;
219166976 rows selected.
Execution Plan
Plan hash value: 189546713
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| T
ime | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 228M| 9155M| 3552M(100)|99
9:59:59 | | |
| 1 | PARTITION LIST SINGLE| | 228M| 9155M| 3552M(100)|99
9:59:59 | KEY | KEY |
| 2 | PARTITION LIST ALL | | 228M| 9155M| 3552M(100)|99
9:59:59 | 1 | 274 |
|* 3 | TABLE ACCESS FULL | GSM_PRR_SUM_NEW | 228M| 9155M| 3552M(100)|99
9:59:59 | KEY | KEY |
Predicate Information (identified by operation id):
3 - filter(TO_CHAR(INTERNAL_FUNCTION("A1"."LOAD_DTTM")) LIKE '%MAR%')
Note
- dynamic sampling used for this statement (level=2)
Statistics
38 recursive calls
107 db block gets
2667792 consistent gets
561765 physical reads
0 redo size
2841422984 bytes sent via SQL*Net to client
24108883 bytes received via SQL*Net from client
2191671 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
219166976 rows processed
SQL>
Thanks,
Manish

How to change the explain plan for currently running query?

Hi All,
I am using Oracle enterprise 9i edition. I have a query which frames dynamically and running in the database. I noticed a table with 31147758 rows
in the query which has no indexes and taking more time to process. I tried to create an INdex on that table. I know the query is already running with a FULL table scan. Is it possible to change the explain plan for the current running query to consider the INDEX?
[code]
SELECT /*+ USE_HASH (c,e,b,a) */
d.att_fcc extrt_prod_dim_id,
d.att_fcc compr_prod_dim_id,
a.glbl_uniq_id glbl_uniq_id,
to_date(c.dit_code,'RRRRMMDD')STRT_DT,
(to_date(c.dit_code,'RRRRMMDD')+150)END_DT,
a.pat_nbr pat_id,
a.rxer_id       rxer_id,
e.rxer_geog_id rxer_geog_id,
a.pharmy_id pharmy_id,
a.pscr_pack_id pscr_pack_id,
a.dspnsd_pack_id dspnsd_pack_id,
DENSE_RANK () OVER (PARTITION BY a.pat_nbr ORDER BY c.dit_code) daterank,
COUNT( DISTINCT d.att_fcc ) OVER (PARTITION BY a.pat_nbr, c.dit_code) event_cnt
DENSE_RANK () OVER (PARTITION BY a.pat_nbr,
d.att_fcc
ORDER BY c.dit_code) prodrank,
DENSE_RANK () OVER (PARTITION BY a.pat_nbr,
d.att_fcc
ORDER BY c.dit_code DESC) stoprank
FROM
pd_dimitems c,
   pd_pack_attribs   d ,
    lrx_tmp_rxer_geog e,
    lrx_tmp_pat_daterank p,
    lrx_tmp_valid_fact_link     a
    WHERE c.dit_id = a.tm_id
    AND   e.rxer_id = a.rxer_id
    AND   a.glbl_uniq_id = p.glbl_uniq_id
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AND   a.pscr_pack_id = d.att_dit_id
[/code]
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Why do you think using Indexes will improve the performance of the query? How many rows this query is returning? Optimizer might chose a Full table scan when it finds out that Index plan might not be useful. Why are you using /*+ USE_HASH (c,e,b,a) */ hint? This Hint will force oracle to use Full table scan instead of using the index. Try removing it and see if the plan changes.
Regards,

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I have a statement with a decode function in the where clause like this:
AND decode(:cropcode,-1,'-1',sdu.u_crop_group) = decode(:cropcode,-1,'-1',:cropcode)When I a pass -1 as parameter for cropgroup the filter would result in "AND '-1' = '-1' and the statement is executed in less than 2 seconds. When I leave out this where clause it takes almost 18 seconds. The result is the same so I don't understand why the explain plan is so much different and why not using index scans in the statement without decode.
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*explain 1*
{code}
SQL Statement which produced this data:
select * from table(dbms_xplan.display)
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)|
| 0 | SELECT STATEMENT | | 7080 | 2413K| | 43611 (2)|
| 1 | SORT ORDER BY | | 7080 | 2413K| 5224K| 43611 (2)|
|* 2 | FILTER | | | | | |
|* 3 | HASH JOIN | | 7156 | 2438K| | 43075 (2)|
| 4 | TABLE ACCESS FULL | DWH_ABS_DETERMINATION | 17745 | 363K| | 83 (0)|
|* 5 | HASH JOIN OUTER | | 7156 | 2292K| | 42991 (2)|
|* 6 | HASH JOIN | | 7156 | 1355K| | 42907 (2)|
|* 7 | HASH JOIN | | 6987 | 1187K| | 19170 (2)|
|* 8 | HASH JOIN | | 6947 | 963K| | 10376 (1)|
|* 9 | TABLE ACCESS BY INDEX ROWID | ALIQUOT | 3 | 144 | | 3 (0)|
| 10 | NESTED LOOPS | | 6907 | 897K| | 8577 (1)|
|* 11 | HASH JOIN | | 2264 | 187K| | 1782 (2)|
| 12 | TABLE ACCESS BY INDEX ROWID | SAMPLE | 190 | 4370 | | 17 (0)|
| 13 | NESTED LOOPS | | 2264 | 152K| | 107 (1)|
| 14 | NESTED LOOPS | | 12 | 552 | | 25 (0)|
|* 15 | TABLE ACCESS FULL | SDG_USER | 12 | 288 | | 13 (0)|
| 16 | TABLE ACCESS BY INDEX ROWID| SDG | 1 | 22 | | 1 (0)|
|* 17 | INDEX UNIQUE SCAN | PK_SDG | 1 | | | 0 (0)|
|* 18 | INDEX RANGE SCAN | FK_SAMPLE_SDG | 597 | | | 2 (0)|
| 19 | TABLE ACCESS FULL | SAMPLE_USER | 1078K| 16M| | 1669 (1)|
|* 20 | INDEX RANGE SCAN | FK_ALIQUOT_SAMPLE | 3 | | | 2 (0)|
| 21 | TABLE ACCESS FULL | ALIQUOT_USER | 3403K| 29M| | 1781 (3)|
| 22 | TABLE ACCESS FULL | TEST | 3423K| 104M| | 8775 (2)|
|* 23 | TABLE ACCESS FULL | RESULT | 3435K| 65M| | 23718 (2)|
| 24 | VIEW | PLATE | 21787 | 2851K| | 84 (2)|
|* 25 | FILTER | | | | | |
| 26 | TABLE ACCESS FULL | PLATE | 21787 | 574K| | 84 (2)|
|* 27 | INDEX UNIQUE SCAN | PK_OPERATOR_GROUP | 1 | 7 | | 0 (0)|
|* 28 | INDEX UNIQUE SCAN | PK_OPERATOR_GROUP | 1 | 7 | | 0 (0)|
|* 29 | INDEX UNIQUE SCAN | PK_OPERATOR_GROUP | 1 | 7 | | 0 (0)|
|* 30 | INDEX UNIQUE SCAN | PK_OPERATOR_GROUP | 1 | 7 | | 0 (0)|
|* 31 | INDEX UNIQUE SCAN | PK_OPERATOR_GROUP | 1 | 7 | | 0 (0)|
Predicate Information (identified by operation id):
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"OPERATOR_GROUP" WHERE "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B1)) AND ("GROUP_ID" IS NULL
OR EXISTS (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP" "OPERATOR_GROUP" WHERE
"OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B2)) AND ("GROUP_ID" IS NULL OR EXISTS (SELECT /*+
*/ 0 FROM "LIMS"."OPERATOR_GROUP" "OPERATOR_GROUP" WHERE "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND
"GROUP_ID"=:B3)) AND ("GROUP_ID" IS NULL OR EXISTS (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP"
"OPERATOR_GROUP" WHERE "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B4)))
3 - access("U_ABS_DETERMINATION"="DETERMINATION_ASSIGNMENT")
5 - access("PLT"."PLATE_ID"(+)="PLATE_ID")
6 - access("TEST_ID"="TEST_ID")
7 - access("ALIQUOT_ID"="ALIQUOT_ID")
8 - access("ALIQUOT_ID"="ALIQUOT_ID")
9 - filter("STATUS"='C' OR "STATUS"='P' OR "STATUS"='V')
11 - access("SAMPLE_ID"="SAMPLE_ID")
15 - filter("U_ABS_DETERMINATION" IS NOT NULL AND "U_CLIENT_TYPE"='QC' AND
"U_WEEK_OF_PROCESSING"=TO_NUMBER(:WEEK) AND "U_YEAR_OF_SAMPLE_DELIVERY"=TO_NUMBER(:YEAR))
17 - access("SDG_ID"="SDG_ID")
18 - access("SDG_ID"="SDG_ID")
20 - access("SAMPLE_ID"="SAMPLE_ID")
23 - filter("NAME"='End result')
25 - filter("GROUP_ID" IS NULL OR EXISTS (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP"
"OPERATOR_GROUP" WHERE "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B1))
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28 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
29 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
30 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
31 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
Note
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{code}
*tkprof 1*
{code}
TKPROF: Release 10.2.0.3.0 - Production on Tue Jan 13 13:21:47 2009
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Trace file: C:\oracle\product\10.2.0\admin\nautp02\udump\nautp02_ora_880.trc
Sort options: default
count = number of times OCI procedure was executed
cpu = cpu time in seconds executing
elapsed = elapsed time in seconds executing
disk = number of physical reads of buffers from disk
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current = number of buffers gotten in current mode (usually for update)
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SELECT sdu.u_crop_group,
sd.name as sdg_name,
ad.variety_name,
ad.batch_number,
a.name as aliquot_name,
sau.u_box_code as box_code,
sau.u_box_position as box_position,
t.name as test_name,
r.original_result,
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concat(chr(a.plate_row + 64),a.plate_column) as plate_position,
au.u_replicate_number as replicate_number
FROM lims_sys.sdg sd,
lims_sys.sdg_user sdu,
lims_sys.sample sa,
lims_sys.sample_user sau,
lims_sys.aliquot a,
lims_sys.aliquot_user au,
lims_sys.test t,
lims_sys.result r,
lims_sys.plate plt,
lims_sys.abs_determination ad
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AND sd.sdg_id = sa.sdg_id
AND sa.sample_id = sau.sample_id
AND sau.sample_id = a.sample_id
AND a.aliquot_id = au.aliquot_id
AND au.aliquot_id = t.aliquot_id
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Parse 1 0.00 0.00 0 0 0 0
Execute 1 1.15 1.16 0 0 0 0
Fetch 1 8.53 16.10 227649 241266 0 500
total 3 9.68 17.27 227649 241266 0 500
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: ALL_ROWS
Parsing user id: 97
Rows Row Source Operation
500 SORT ORDER BY (cr=241266 pr=227649 pw=0 time=16104631 us)
21311 FILTER (cr=241266 pr=227649 pw=0 time=16246749 us)
21311 HASH JOIN (cr=241266 pr=227649 pw=0 time=16225434 us)
17745 TABLE ACCESS FULL DWH_ABS_DETERMINATION (cr=374 pr=0 pw=0 time=69 us)
21311 HASH JOIN RIGHT OUTER (cr=240892 pr=227649 pw=0 time=16170607 us)
21895 VIEW PLATE (cr=316 pr=0 pw=0 time=43825 us)
21895 FILTER (cr=316 pr=0 pw=0 time=43823 us)
21895 TABLE ACCESS FULL PLATE (cr=316 pr=0 pw=0 time=31 us)
0 INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
21311 HASH JOIN (cr=240576 pr=227649 pw=0 time=16106174 us)
21311 HASH JOIN (cr=133559 pr=121596 pw=0 time=9594130 us)
21311 HASH JOIN (cr=94323 pr=83281 pw=0 time=6917067 us)
21311 HASH JOIN (cr=86383 pr=75547 pw=0 time=5509672 us)
7776 HASH JOIN (cr=8134 pr=0 pw=0 time=285364 us)
7776 TABLE ACCESS BY INDEX ROWID SAMPLE (cr=572 pr=0 pw=0 time=27152 us)
7876 NESTED LOOPS (cr=377 pr=0 pw=0 time=488287 us)
99 HASH JOIN (cr=160 pr=0 pw=0 time=4168 us)
99 TABLE ACCESS FULL SDG_USER (cr=53 pr=0 pw=0 time=1209 us)
5719 TABLE ACCESS FULL SDG (cr=107 pr=0 pw=0 time=17 us)
7776 INDEX RANGE SCAN FK_SAMPLE_SDG (cr=217 pr=0 pw=0 time=623 us)(object id 45990)
1079741 TABLE ACCESS FULL SAMPLE_USER (cr=7562 pr=0 pw=0 time=24 us)
3307948 TABLE ACCESS FULL ALIQUOT (cr=78249 pr=75547 pw=0 time=3331129 us)
3406836 TABLE ACCESS FULL ALIQUOT_USER (cr=7940 pr=7734 pw=0 time=556 us)
3406832 TABLE ACCESS FULL TEST (cr=39236 pr=38315 pw=0 time=3413192 us)
3406832 TABLE ACCESS FULL RESULT (cr=107017 pr=106053 pw=0 time=6848487 us)
0 INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
0 INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
0 INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
0 INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
select 'x'
from
dual
call count cpu elapsed disk query current rows
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 1 0.00 0.00 0 0 0 1
total 3 0.00 0.00 0 0 0 1
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 97
Rows Row Source Operation
1 FAST DUAL (cr=0 pr=0 pw=0 time=3 us)
begin :id := sys.dbms_transaction.local_transaction_id; end;
call count cpu elapsed disk query current rows
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 1
Fetch 0 0.00 0.00 0 0 0 0
total 2 0.00 0.00 0 0 0 1
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 97
OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS
call count cpu elapsed disk query current rows
Parse 3 0.00 0.00 0 0 0 0
Execute 3 1.15 1.16 0 0 0 1
Fetch 2 8.53 16.10 227649 241266 0 501
total 8 9.68 17.27 227649 241266 0 502
Misses in library cache during parse: 1
Misses in library cache during execute: 1
OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS
call count cpu elapsed disk query current rows
Parse 30 0.00 0.00 0 0 0 0
Execute 30 0.00 0.00 0 0 0 0
Fetch 30 0.00 0.00 0 40 0 10
total 90 0.00 0.00 0 40 0 10
Misses in library cache during parse: 0
3 user SQL statements in session.
30 internal SQL statements in session.
33 SQL statements in session.
Trace file: C:\oracle\product\10.2.0\admin\nautp02\udump\nautp02_ora_880.trc
Trace file compatibility: 10.01.00
Sort options: default
8 sessions in tracefile.
3 user SQL statements in trace file.
30 internal SQL statements in trace file.
33 SQL statements in trace file.
6 unique SQL statements in trace file.
633 lines in trace file.
23 elapsed seconds in trace file.
{code}

explain 2
SQL Statement which produced this data:
select * from table(dbms_xplan.display)
PLAN_TABLE_OUTPUT
| Id | Operation                               | Name                     | Rows | Bytes | Cost (%CPU)|
|   0 | SELECT STATEMENT                        |                          |    71 | 24779 |   857   (1)|
|   1 | SORT ORDER BY                          |                          |    71 | 24779 |   857   (1)|
|* 2 |   FILTER                                |                          |       |       |            |
|* 3 |    TABLE ACCESS BY INDEX ROWID          | RESULT                   |     1 |    20 |     4   (0)|
|   4 |     NESTED LOOPS                        |                          |    72 | 25128 |   856   (1)|
|   5 |      NESTED LOOPS                       |                          |    70 | 23030 |   576   (1)|
|* 6 |       HASH JOIN OUTER                   |                          |    69 | 20493 |   369   (1)|
|   7 |        NESTED LOOPS                     |                          |    69 | 11247 |   285   (0)|
|   8 |         NESTED LOOPS                    |                          |    69 | 10626 |   147   (0)|
|   9 |          NESTED LOOPS                   |                          |    23 | 2438 |    78   (0)|
| 10 |           NESTED LOOPS                  |                          |    23 | 2070 |    32   (0)|
| 11 |            NESTED LOOPS                 |                          |     1 |    67 |    15   (0)|
| 12 |             NESTED LOOPS                |                          |     1 |    45 |    14   (0)|
|* 13 |              TABLE ACCESS FULL          | SDG_USER                 |     1 |    24 |    13   (0)|
| 14 |              TABLE ACCESS BY INDEX ROWID| DWH_ABS_DETERMINATION    |     1 |    21 |     1   (0)|
|* 15 |               INDEX UNIQUE SCAN         | PK_DWH_ABS_DETERMINATION |     1 |       |     0   (0)|
| 16 |             TABLE ACCESS BY INDEX ROWID | SDG                      |     1 |    22 |     1   (0)|
|* 17 |              INDEX UNIQUE SCAN          | PK_SDG                   |     1 |       |     0   (0)|
| 18 |            TABLE ACCESS BY INDEX ROWID | SAMPLE                   |   190 | 4370 |    17   (0)|
|* 19 |             INDEX RANGE SCAN            | FK_SAMPLE_SDG            |   597 |       |     2   (0)|
| 20 |           TABLE ACCESS BY INDEX ROWID   | SAMPLE_USER              |     1 |    16 |     2   (0)|
|* 21 |            INDEX UNIQUE SCAN            | PK_SAMPLE_USER           |     1 |       |     1   (0)|
|* 22 |          TABLE ACCESS BY INDEX ROWID    | ALIQUOT                  |     3 |   144 |     3   (0)|
|* 23 |           INDEX RANGE SCAN              | FK_ALIQUOT_SAMPLE        |     3 |       |     2   (0)|
| 24 |         TABLE ACCESS BY INDEX ROWID     | ALIQUOT_USER             |     1 |     9 |     2   (0)|
|* 25 |          INDEX UNIQUE SCAN              | PK_ALIQUOT_USER          |     1 |       |     1   (0)|
| 26 |        VIEW                             | PLATE                    | 21787 | 2851K|    84   (2)|
|* 27 |         FILTER                          |                          |       |       |            |
| 28 |          TABLE ACCESS FULL              | PLATE                    | 21787 |   574K|    84   (2)|
|* 29 |          INDEX UNIQUE SCAN              | PK_OPERATOR_GROUP        |     1 |     7 |     0   (0)|
| 30 |       TABLE ACCESS BY INDEX ROWID       | TEST                     |     1 |    32 |     3   (0)|
|* 31 |        INDEX RANGE SCAN                 | FK_TEST_ALIQUOT          |     1 |       |     2   (0)|
|* 32 |      INDEX RANGE SCAN                   | FK_RESULT_TEST           |     2 |       |     2   (0)|
|* 33 |    INDEX UNIQUE SCAN                    | PK_OPERATOR_GROUP        |     1 |     7 |     0   (0)|
|* 34 |    INDEX UNIQUE SCAN                    | PK_OPERATOR_GROUP        |     1 |     7 |     0   (0)|
|* 35 |    INDEX UNIQUE SCAN                    | PK_OPERATOR_GROUP        |     1 |     7 |     0   (0)|
|* 36 |    INDEX UNIQUE SCAN                    | PK_OPERATOR_GROUP        |     1 |     7 |     0   (0)|
Predicate Information (identified by operation id):
   2 - filter(("GROUP_ID" IS NULL OR EXISTS (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP"
              "OPERATOR_GROUP" WHERE "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B1)) AND ("GROUP_ID"
              IS NULL OR EXISTS (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP" "OPERATOR_GROUP" WHERE
              "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B2)) AND ("GROUP_ID" IS NULL OR EXISTS
              (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP" "OPERATOR_GROUP" WHERE
              "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B3)) AND ("GROUP_ID" IS NULL OR EXISTS
              (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP" "OPERATOR_GROUP" WHERE
              "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B4)))
   3 - filter("NAME"='End result')
   6 - access("PLT"."PLATE_ID"(+)="PLATE_ID")
13 - filter("U_ABS_DETERMINATION" IS NOT NULL AND "U_CLIENT_TYPE"='QC' AND
              "U_WEEK_OF_PROCESSING"=TO_NUMBER(:WEEK) AND "U_YEAR_OF_SAMPLE_DELIVERY"=TO_NUMBER(:YEAR) AND
              DECODE(:CROPCODE,(-1),'-1',"U_CROP_GROUP")=DECODE(:CROPCODE,(-1),'-1',:CROPCODE))
15 - access("U_ABS_DETERMINATION"="DETERMINATION_ASSIGNMENT")
17 - access("SDG_ID"="SDG_ID")
19 - access("SDG_ID"="SDG_ID")
21 - access("SAMPLE_ID"="SAMPLE_ID")
22 - filter("STATUS"='C' OR "STATUS"='P' OR "STATUS"='V')
23 - access("SAMPLE_ID"="SAMPLE_ID")
25 - access("ALIQUOT_ID"="ALIQUOT_ID")
27 - filter("GROUP_ID" IS NULL OR EXISTS (SELECT /*+ */ 0 FROM "LIMS"."OPERATOR_GROUP"
              "OPERATOR_GROUP" WHERE "OPERATOR_ID"="LIMS$OPERATOR_ID"() AND "GROUP_ID"=:B1))
29 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
31 - access("ALIQUOT_ID"="ALIQUOT_ID")
32 - access("TEST_ID"="TEST_ID")
33 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
34 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
35 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
36 - access("GROUP_ID"=:B1 AND "OPERATOR_ID"="LIMS$OPERATOR_ID"())
Note
   - 'PLAN_TABLE' is old version
tkprof 2
TKPROF: Release 10.2.0.3.0 - Production on Tue Jan 13 13:28:26 2009
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Trace file: C:\oracle\product\10.2.0\admin\nautp02\udump\nautp02_ora_5456.trc
Sort options: default
count    = number of times OCI procedure was executed
cpu      = cpu time in seconds executing
elapsed = elapsed time in seconds executing
disk     = number of physical reads of buffers from disk
query    = number of buffers gotten for consistent read
current = number of buffers gotten in current mode (usually for update)
rows     = number of rows processed by the fetch or execute call
SELECT sdu.u_crop_group,
       sd.name as sdg_name,
       ad.variety_name,
       ad.batch_number,
       a.name as aliquot_name,
       sau.u_box_code as box_code,
       sau.u_box_position as box_position,
       t.name as test_name,
       r.original_result,
       plt.name as plate_name,
       concat(chr(a.plate_row + 64),a.plate_column) as plate_position,
       au.u_replicate_number as replicate_number
FROM lims_sys.sdg sd,
     lims_sys.sdg_user sdu,
     lims_sys.sample sa,
     lims_sys.sample_user sau,
     lims_sys.aliquot a,
     lims_sys.aliquot_user au,
     lims_sys.test t,
     lims_sys.result r,
     lims_sys.plate plt,
     lims_sys.abs_determination ad
WHERE sd.sdg_id = sdu.sdg_id
AND sd.sdg_id = sa.sdg_id
AND sa.sample_id = sau.sample_id
AND sau.sample_id = a.sample_id
AND a.aliquot_id = au.aliquot_id
AND au.aliquot_id = t.aliquot_id
AND t.test_id = r.test_id
AND plt.plate_id (+) = a.plate_id
AND sdu.u_abs_determination = ad.determination_assignment
AND a.status IN ('V','P','C')
AND r.name = 'End result'
AND sdu.u_client_type = 'QC'
AND sdu.u_year_of_sample_delivery = (:year)
AND sdu.u_week_of_processing = (:week)
AND decode(:cropcode,-1,'-1',sdu.u_crop_group) = decode(:cropcode,-1,'-1',:cropcode)
ORDER BY box_code, box_position, replicate_number
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.01       0.00          0          0          0           0
Execute      1      0.45       0.87          0          0          0           0
Fetch        1      1.00       0.99          0     221420          0         500
total        3      1.46       1.86          0     221420          0         500
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: ALL_ROWS
Parsing user id: 97
Rows     Row Source Operation
    500 SORT ORDER BY (cr=221420 pr=0 pw=0 time=992364 us)
21311   FILTER (cr=221420 pr=0 pw=0 time=1128970 us)
21311    TABLE ACCESS BY INDEX ROWID RESULT (cr=221420 pr=0 pw=0 time=1086345 us)
42623     NESTED LOOPS (cr=217549 pr=0 pw=0 time=30006317 us)
21311      NESTED LOOPS (cr=174880 pr=0 pw=0 time=809278 us)
21311       NESTED LOOPS (cr=110117 pr=0 pw=0 time=553538 us)
21311        HASH JOIN OUTER (cr=46182 pr=0 pw=0 time=319102 us)
21311         TABLE ACCESS BY INDEX ROWID ALIQUOT (cr=45866 pr=0 pw=0 time=193037 us)
29088          NESTED LOOPS (cr=39885 pr=0 pw=0 time=320084 us)
   7776           NESTED LOOPS (cr=24267 pr=0 pw=0 time=156721 us)
   7776            NESTED LOOPS (cr=937 pr=0 pw=0 time=78954 us)
     99             NESTED LOOPS (cr=454 pr=0 pw=0 time=3826 us)
     99              NESTED LOOPS (cr=253 pr=0 pw=0 time=2833 us)
     99               TABLE ACCESS FULL SDG_USER (cr=53 pr=0 pw=0 time=1531 us)
     99               TABLE ACCESS BY INDEX ROWID DWH_ABS_DETERMINATION (cr=200 pr=0 pw=0 time=956 us)
     99                INDEX UNIQUE SCAN PK_DWH_ABS_DETERMINATION (cr=101 pr=0 pw=0 time=438 us)(object id 46965)
     99              TABLE ACCESS BY INDEX ROWID SDG (cr=201 pr=0 pw=0 time=707 us)
     99               INDEX UNIQUE SCAN PK_SDG (cr=101 pr=0 pw=0 time=330 us)(object id 46071)
   7776             TABLE ACCESS BY INDEX ROWID SAMPLE (cr=483 pr=0 pw=0 time=16261 us)
   7776              INDEX RANGE SCAN FK_SAMPLE_SDG (cr=217 pr=0 pw=0 time=562 us)(object id 45990)
   7776            TABLE ACCESS BY INDEX ROWID SAMPLE_USER (cr=23330 pr=0 pw=0 time=64710 us)
   7776             INDEX UNIQUE SCAN PK_SAMPLE_USER (cr=15554 pr=0 pw=0 time=33728 us)(object id 46012)
21311           INDEX RANGE SCAN FK_ALIQUOT_SAMPLE (cr=15618 pr=0 pw=0 time=43423 us)(object id 45346)
21895         VIEW PLATE (cr=316 pr=0 pw=0 time=43833 us)
21895          FILTER (cr=316 pr=0 pw=0 time=21936 us)
21895           TABLE ACCESS FULL PLATE (cr=316 pr=0 pw=0 time=37 us)
      0           INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
21311        TABLE ACCESS BY INDEX ROWID ALIQUOT_USER (cr=63935 pr=0 pw=0 time=182479 us)
21311         INDEX UNIQUE SCAN PK_ALIQUOT_USER (cr=42624 pr=0 pw=0 time=99160 us)(object id 45386)
21311       TABLE ACCESS BY INDEX ROWID TEST (cr=64763 pr=0 pw=0 time=219096 us)
21311        INDEX RANGE SCAN FK_TEST_ALIQUOT (cr=42669 pr=0 pw=0 time=129354 us)(object id 46222)
21311      INDEX RANGE SCAN FK_RESULT_TEST (cr=42669 pr=0 pw=0 time=125893 us)(object id 45940)
      0    INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
      0    INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
      0    INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
      0    INDEX UNIQUE SCAN PK_OPERATOR_GROUP (cr=0 pr=0 pw=0 time=0 us)(object id 45769)
select 'x'
from
dual
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        1      0.00       0.00          0          0          0           1
total        3      0.00       0.00          0          0          0           1
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 97
Rows     Row Source Operation
      1 FAST DUAL (cr=0 pr=0 pw=0 time=6 us)
begin :id := sys.dbms_transaction.local_transaction_id; end;
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          2           0
Execute      1      0.00       0.00          0          0          0           1
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          0          0          2           1
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: ALL_ROWS
Parsing user id: 97
OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS
call     count       cpu    elapsed       disk      query    current        rows
Parse        3      0.01       0.00          0          0          2           0
Execute      3      0.45       0.87          0          0          0           1
Fetch        2      1.00       0.99          0     221420          0         501
total        8      1.46       1.87          0     221420          2         502
Misses in library cache during parse: 2
Misses in library cache during execute: 2
OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS
call     count       cpu    elapsed       disk      query    current        rows
Parse       43      0.01       0.00          0          0         12           0
Execute    128      0.00       0.01          0          0          0           0
Fetch      178      0.00       0.00          0        383          0         465
total      349      0.01       0.02          0        383         12         465
Misses in library cache during parse: 5
Misses in library cache during execute: 5
    3 user SQL statements in session.
128 internal SQL statements in session.
131 SQL statements in session.
Trace file: C:\oracle\product\10.2.0\admin\nautp02\udump\nautp02_ora_5456.trc
Trace file compatibility: 10.01.00
Sort options: default
       1 session in tracefile.
       3 user SQL statements in trace file.
     128 internal SQL statements in trace file.
     131 SQL statements in trace file.
      19 unique SQL statements in trace file.
    1352 lines in trace file.
     287 elapsed seconds in trace file.

How to proceed further once the explain plan and trace files are generated?

Hi Friends,
I need to improve the performance of on of the views that i am working on.
As suggested in the thread - http://forums.oracle.com/forums/thread.jspa?threadID=863295&tstart=0 , i gave generated the explain plan and the trace file.
From the explain plan, we can see the expensive operations for the query.
Can any one please tell, how to proceed further from here on i.e. how to make this expensive operations less expensive?
For ex: FULL TABLE SCAN might be an expensive operation when the table has indexes.In such cases, how can we avoid such operations to make query faster?
Regards,
Sreekanth Munagala.

Hi Veena,
An earlier post by you regarding P45 is as below
Starter report P45(3) / P46 efiling for UK
from my understanding though i have not worked on GB Payroll you have said that you deleted IT 65 details of leaver,however there must be clusters generated in system from where the earlier data needs to be deleted and may be that is why you are facing the issue.
In Indian payroll when we execute text file for efiling of tax after challan mapping all the data compiles and sits in PCL cluster and therefore we are unable to generate form 16 with proper output,here we delete the clusters and rerun again the mappings and then check form 16.
Hope this might help you,Experts have suggested you earlier also,they may correct me for this.
Salil

Not able to use EXPLAIN PLAN in Toad

hi,
I am not able to use Explain Plan in Toad. The error it gives is the table PLAN_TABLE doesn't exit.
But after seeing this error I did run the script "UTLXPLAN.sql" in order to create the plan_table table.
After installing the above table I am not able to use EXPLAIN_PLAN from toad, Its giving same error Table PLAN_TABLE doesn't exit though i created it successfully in the proper schema.
Thanks in advance
Ram

check and post.
SQL> select owner from dba_tables where table_name='PLAN_TABLE';
before using toad ,first u should connect to sqlplus by that user and issue
SET AUTOTRACE ON.
Kuljeet

How can i paste the explain plan from toad..

Hello all
I tried taking a snap of the explain plan from toad but in this forum the paste option is disabled...please help

964145 wrote:
I tried taking a snap of the explain plan from toad but in this forum the paste option is disabled...please helpI don't know, but it is a waste of time since explain plans from Toad are not useful.
Please read the forum FAQ on providing information for a tuning request, it describes how to generate an explain plan that can be shared.
{message:id=9360003}
This is an example.
SQL> explain plan for
2 select * from dual;
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 3543395131
| Id | Operation         | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |      |     1 |     2 |     2   (0)| 00:00:01 |
|   1 | TABLE ACCESS FULL| DUAL |     1 |     2 |     2   (0)| 00:00:01 |
--------------------------------------------------------------------------

What privileges or role is required for user to acces the explain plan?

Hi mates,
Can anyone pls tell me what privileges or roles(grants) are requred for a user to access the explain plan in oORACLE 8i 8174..
I think the select any dictionary is not valid for explain plan accessibility in 8i.
Cheers.

I already had that... Just that a user (not a dba) requires access to the explain plan and I dont want to grant him a dba role.
Are you aware of any other grant I can give to the user?

Why can the explain plan be different from 2 exact set of structures

hi,
i have from a view some base tables let's say A , B, C & D
this query is running very slow . so from the same database , i created tables A1 , B1, C1,& D1 from the above tables.
i created some new indexes on A1 to D1 tables and the results returned to me is fast.
i did an exlain plan
so i drop the indexes on the original A to D table and created the new indexes as per A1 to D1 and analyzed them. and i also did an explain plan
but the query is still running slow and also the explain plan is different to the one from A1 to D1 (the one that running fast)
pls help me to understand how/why can this happen ?
tks & rdgs

hi,
precisely i could have been providing insufficient information but i am too inexperienced to be able to give you the required information and i am also not very sure where i could get the info so that you all can advise me further.
but this is from the user_tables , the only difference i see is that
under LOGGING table A to E is 'YES'
TABLE_NAME     TABLESPACE_NAME     PCT_FREE     LOGGING     BACKED_UP     NUM_ROWS     BLOCKS     CACHE     TABLE_LOCK     PARTITIONED
A1          OWNER1          10          NO          N     37332          883         N     ENABLED     NO
B1          OWNER1          10          NO          N     43458          861         N     ENABLED     NO
C1          OWNER1          10          NO          N     823828          7826         N     ENABLED     NO
D1          OWNER1          10          NO          N     881176          14646         N     ENABLED     NO
E1          OWNER1          10          NO          N     18868          223         N     ENABLED     NO
A          OWNER1          10          YES          N     37040          880         N     ENABLED     NO
B          OWNER1          10          YES          N     43386          880         N     ENABLED     NO
C          OWNER1          10          YES          N     823820          7684         N     ENABLED     NO
D          OWNER1          50          YES          N     880948          26624         N     ENABLED     NO
E          OWNER1          10          YES          N     18690          244         N     ENABLED     NOtks & rdgs

Interpreting the Explain plan

DB version : 10.2.0.4
After looking for Full Table Scan (in Large tables) , what is the next thing i should be looking for in an Explain Plan?

Take the explain plan as an idea a tourist has to collect a bunch of stuff in your hometown. You ( as a local guy) will see quite quickly if the idea of collecting everything on the main routes in big shops by car (hash join) or doing a walk in one or two streets with small shops (nested loop) will perform better. Stangers will not.
ORACLE already knows more about the data than a tourist about your hometome, so if it uses a method which is "suboptimal" it needs someone with good knowlage about the data to do better. So make sure you know your datamodel, contents, indexes, data and then you can help ORACLE with additional indexes, hints etc. without knowlege every plan of ORACLE can not be juged.

Why the explain plan incorrent?

I have a sql in oracle10.2.03:
select *
from (select a.*
from t_user a, t_message b
where b.user_id = a.row_id and a.user_type = 1
order by b.happen_time desc)
where rownum <= 5
there are indexes on column a.user_type,b.user_id,b.happen_time, and has been analyzed. a.user_type=1 only have 1/1000 records
the explain plan is below:
cost Cardinary Bytes
SELECT STATEMENT, GOAL = ALL_ROWS 30 5 3790
COUNT STOPKEY
VIEW BMTEST 30 6 4548
NESTED LOOPS 30 6 1158
TABLE ACCESS BY INDEX ROWID BMTEST T_MESSAGE 13 1524118 24385888
INDEX FULL SCAN DESCENDING BMTEST IDX_MESSAGE_2 1 168
TABLE ACCESS BY INDEX ROWID BMTEST T_USER 1 1 177
INDEX UNIQUE SCAN BMTEST PK_USER 1 1
Oracle use the index full scan descending on the happen_time. the cost only has 30.
After I add hint on the sql on the user_id of t_message
select *
from (select /*+index (b idx_message_1)*/ a.*
from t_user a, t_message b
where b.user_id = a.row_id and a.user_type = 1
order by b.happen_time desc)
where rownum <= 5
the explain plan change to:
cost Cardinary Bytes
SELECT STATEMENT, GOAL = ALL_ROWS 5020 5 3790
COUNT STOPKEY
VIEW BMTEST 5020 54707 41467906
SORT ORDER BY STOPKEY 5020 54707 10558451
TABLE ACCESS BY INDEX ROWID BMTEST T_MESSAGE 26 515 8240
NESTED LOOPS 2707 54707 10558451
TABLE ACCESS BY INDEX ROWID BMTEST T_USER 1 106 18762
INDEX RANGE SCAN BMTEST IDX_USER_2 1 106
INDEX RANGE SCAN BMTEST IDX_MESSAGE_1 1 515
INDEX UNIQUE SCAN BMTEST PK_USER 1 1
The cost is 5020, but the execute usage time only is 100ms, and the first SQL does not add hint usage 20s.
Why the lower cost waste more time, if the cost caculate is incorrect?
Edited by: [email protected] on Sep 11, 2008 9:14 PM

[email protected] wrote:
But i am afraid i use a misunderstand title for this post,my doubt is why oracle get a large cost with the sql execute few time but get a small cost with the sql execute long time.The cost of a query isn't a particularly good proxy for runtime. It is perfectly reasonable for a query with a cost of 1000 to run more quickly than a query with a cost of 100. The cost of queries is only directly comparable between different plans in the same 10053 trace file.
[email protected] wrote:
All the indexed columns are both analyzed by the command or by DBMS_STATS package and the cpu costing is enabled.But what order are the commands being run? And why is the ANALYZE command being used to gather optimizer stats.
In the first plan:
INDEX FULL SCAN DESCENDING BMTEST IDX_MESSAGE_2 1 168
Why this index full scan cost only 1? how did oracle get this number? Is there formula to caculate the cost of index full scan? I have read the article named "Cost Based Oracle Fundamentals" and there is no introduce how to caculate it.
I think this abnormality cost makes the cost of next step "NESTED LOOPS" very smal and finally lead this abnormality result.1) Which article are you talking about? Are you talking about Jonathan Lewis's book "Cost Based Oracle Fundamentals"? Or are you referring to a different article somewhere?
2) Can you post the query plans formatted via DBMS_XPLAN.DISPLAY (including the predicate information and enclose the output in the \[pre\] and \[pre\] tags to preserve white space?
Justin
Justin

Help to understand the explain plan

Hi, Everyone,
i have query :
INSERT INTO ICM_UPSEL_1_ALL
select a.customer_no,a.pr_code_bbl,min(b.pr_code_pmm) pr_code_pmm,a.score,a.price_diff,a.flag
from ICM_UPSEL_MIN_PRDIFF_1 a, icm_pre b
where a.customer_no = b.customer_no
and a.pr_code_bbl=b.pr_code_bbl
and a.score = b.score
and a.flag = b.flag
and a.price_diff = b.price_diff
and b.price_diff > 0
and b.score >=0.5
and b.flag = 1
and b.price_diff > 0 and b.price_diff <= 10
group by a.customer_no,a.pr_code_bbl,a.score,a.price_diff,a.flag
This query is running in a pl/sql procedure. The explain plan for this query is :
Plan hash value: 3124235498
| Id | Operation                       | Name                           | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | INSERT STATEMENT                |                                |     1 |   143 |     4 (25)| 00:00:01 |
|   1 | LOAD TABLE CONVENTIONAL        | ICM_UPSEL_1_ALL        |       |       |            |          |
|   2 |   HASH GROUP BY                 |                                |     1 |   143 |     4 (25)| 00:00:01 |
|   3 |    NESTED LOOPS                 |                                |       |       |            |          |
|   4 |     NESTED LOOPS                |                                |     1 |   143 |     3   (0)| 00:00:01 |
|* 5 |      TABLE ACCESS BY INDEX ROWID| ICM_UPSEL_MIN_PRDIFF_1 |     1 |    65 |     1   (0)| 00:00:01 |
|* 6 |       INDEX RANGE SCAN          | MPD_1_FLAG_IDX                 |     1 |       |     1   (0)| 00:00:01 |
|* 7 |      INDEX RANGE SCAN           | ICM_PRE_FLAG_IDX               |     1 |       |     2   (0)| 00:00:01 |
|* 8 |     TABLE ACCESS BY INDEX ROWID | ICM_PRE                |     1 |    78 |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   5 - filter("A"."PRICE_DIFF">0 AND "A"."SCORE">=0.5 AND "A"."PRICE_DIFF"<=10)
   6 - access("A"."FLAG"=1)
   7 - access("B"."FLAG"=1)
   8 - filter("B"."PRICE_DIFF"<=10 AND "B"."SCORE">=0.5 AND "B"."PRICE_DIFF">0 AND
              "A"."CUSTOMER_NO"="B"."CUSTOMER_NO" AND "A"."PR_CODE_BBL"="B"."PR_CODE_BBL" AND "A"."SCORE"="B"."SCORE"
              AND "A"."PRICE_DIFF"="B"."PRICE_DIFF")
This query is running for 10 hours now and no result yet. Could anyone please help me where is going wrong... why is it taking so much time to insert the data...
The number of rows in ICM_UPSEL_MIN_PRDIFF_1 : 84,858
The number of rows in icm_pre : 455,500,944
All the columns are indexed.
My database version is 11.1.0.6 running on windows server 2003 R2.
Thanks in advance

Hi, Nikolay,
Please see the results below;
SELECT * FROM DBA_TAB_COL_STATISTICS
WHERE OWNER = 'SAST' AND TABLE_NAME = 'ICM_UPSEL_MIN_PRDIFF_1' AND COLUMN_NAME = 'FLAG';
TABLE_NAME
COLUMN_NAME
NUM_DISTINCT
LOW_VALUE
HIGH_VALUE
DENSITY
NUM_NULLS
NUM_BUCKETS
LAST_ANALYZED
SAMPLE_SIZE
GLOBAL_STATS
USER_STATS
AVG_COL_LEN
HISTOGRAM
SAST    ICM_UPSEL_MIN_PRDIFF_1    FLAG    1    C102    C102    0.00000584543291182618    0    1    16/07/13 10:01:42    5544    YES    NO    3    FREQUENCY
SELECT * FROM DBA_TAB_STATISTICS WHERE OWNER = 'SAST' AND TABLE_NAME = 'ICM_UPSEL_MIN_PRDIFF_1';
TABLE_NAME
PARTITION_NAME
PARTITION_POSITION
SUBPARTITION_NAME
SUBPARTITION_POSITION
OBJECT_TYPE
NUM_ROWS
BLOCKS
EMPTY_BLOCKS
AVG_SPACE
CHAIN_CNT
AVG_ROW_LEN
AVG_SPACE_FREELIST_BLOCKS
NUM_FREELIST_BLOCKS
AVG_CACHED_BLOCKS
AVG_CACHE_HIT_RATIO
SAMPLE_SIZE
LAST_ANALYZED
GLOBAL_STATS
USER_STATS
STATTYPE_LOCKED
STALE_STATS
SAST    ICM_UPSEL_MIN_PRDIFF_1
TABLE    84858    874    0    0    0    62    0    0
84858    16/07/13 10:02:00    YES    NO
NO
Thanks & Regards
Su

Facing Merge Join Cartersian in the explain plan after adding gl periods

Hi All
I have added gl periods table to the below query , checked the explain plan and it shows merge join cartesian. This query is taking long time to fetch the results.
Need help ASAP , Please let me know where i am going wrong . Any suggestions will be appreciated.
SELECT gljh.period_name, gljh.ledger_id, gljh.je_source,
glcc.segment2,
SUM ( NVL (gljl.accounted_dr, 0)
- NVL (gljl.accounted_cr, 0)
) total_amt,
gljh.currency_code
FROM gl_je_headers gljh,
gl_je_lines gljl,
gl_code_combinations glcc,
gl_periods gps
WHERE 1=1
AND gljh.period_name = gps.period_name
AND gljl.period_name = gps.period_name
AND gps.period_set_name = 'MCD_MONTH_'
AND gps.start_date >= :p_from_date
AND gps.start_date <= :p_to_date
AND gljh.ledger_id = :p_ledger_id
AND gljh.je_header_id = gljl.je_header_id
AND gljl.code_combination_id = glcc.code_combination_id
AND glcc.segment2 = '10007'--get_segment2_rec.flex_value
AND gljh.currency_code <> 'STAT'
GROUP BY gljh.je_source,
gljh.period_name,
glcc.segment2,
gljh.ledger_id,
gljh.currency_code
HAVING SUM ( NVL (gljl.accounted_dr, 0)
- NVL (gljl.accounted_cr, 0)
) <> 0;
Plan
SELECT STATEMENT ALL_ROWSCost: 73,146 Bytes: 2,266 Cardinality: 22
     15 FILTER
          14 HASH GROUP BY Cost: 73,146 Bytes: 2,266 Cardinality: 22
               13 FILTER
                    12 NESTED LOOPS Cost: 73,145 Bytes: 61,079 Cardinality: 593
                         9 NESTED LOOPS Cost: 31,603 Bytes: 1,452,780 Cardinality: 20,754
                              6 MERGE JOIN CARTESIAN Cost: 2,108 Bytes: 394,181 Cardinality: 9,167
                                   2 TABLE ACCESS BY INDEX ROWID TABLE GL.GL_PERIODS Cost: 4 Bytes: 31 Cardinality: 1
                                        1 INDEX RANGE SCAN INDEX (UNIQUE) GL.GL_PERIODS_U2 Cost: 1 Cardinality: 64
                                   5 BUFFER SORT Cost: 2,104 Bytes: 683,988 Cardinality: 56,999
                                        4 TABLE ACCESS BY INDEX ROWID TABLE GL.GL_CODE_COMBINATIONS Cost: 2,104 Bytes: 683,988 Cardinality: 56,999
                                             3 INDEX RANGE SCAN INDEX GL.GL_CODE_COMBINATIONS_N2 Cost: 155 Cardinality: 56,999
                              8 TABLE ACCESS BY INDEX ROWID TABLE GL.GL_JE_LINES Cost: 18 Bytes: 54 Cardinality: 2
                                   7 INDEX RANGE SCAN INDEX GL.GL_JE_LINES_N1 Cost: 3 Cardinality: 37
                         11 TABLE ACCESS BY INDEX ROWID TABLE GL.GL_JE_HEADERS Cost: 2 Bytes: 33 Cardinality: 1
                              10 INDEX UNIQUE SCAN INDEX (UNIQUE) GL.GL_JE_HEADERS_U1 Cost: 1 Cardinality: 1
Thanks
Chandra

Lots of things come into play when you're tuning a query.
An (unformatted) execution plan isn't enough.
Tuning takes time and understanding how (a lot of) things work, there is no ASAP in the world of tuning.
Please post other important details, like your database version, optimizer settings, how/when are table statistics gathered etc.
So, read the following informative threads (and please take your time, this really is important stuff), and adust your thread as needed.
That way you'll have a bigger chance of getting help that makes sense...
Your DBA should/ought to be able to help you in this as well.
Re: HOW TO: Post a SQL statement tuning request - template posting
http://oracle-randolf.blogspot.com/2009/02/basic-sql-statement-performance.html

Calculating the Size(KB) in the explain plan....

Hi
I executed a sql statement in SQL*PLUS and having enabled the tracing in OEM , among others , I read the Size in KiloBytes which the 'TABLE ACCESS FULL' segment of the explain plan returned.....
This number is 5.998,193KB
I used the vsize built-in function in order to get the total number in bytes of the physical representation of all the rows (about 53500) ....
So , I wrote :
select nvl(sum(vsize(farmak_code)),0)+nvl(sum(vsize(emp_name)),0)+nvl(sum(vsize(category)),0)+ .....+.....
from mitroo_farmakou
The result was 5794544 in bytes which is close to 5.998,193KB.
My question is :
The computation of the bytes in the explain plan (TABLE ACCESS FULL segment) is done by adding the vsize of all columns....????
Does anybody Knows...????
Thanks , a lot
Simon

I doubt it. For a large table that would be an incredibly expensive calculation.
I suspect that it is something closer to:
SQL> SELECT * FROM incident;
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=137 Card=15603 Bytes=6818511)
   1    0   TABLE ACCESS (FULL) OF 'INCIDENT' (Cost=137 Card=15603 Bytes=6818511)
SQL> SELECT ROUND(num_rows * avg_row_len)
2 FROM user_tables
3 WHERE table_name = 'INCIDENT';
ROUND(NUM_ROWS*AVG_ROW_LEN)
                    6818449HTH
John

Dynamic sampling coming in the NOTE section of the explain plan.

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