Physical reads

I 'm running the same query against two databases on two different servers, and not seeing the expected results.
Query runs in 6 seconds on server A, and 32 seconds on server B. The database on B is a copy of the database on A, same blocksize, same db_file_multiblock_read_count.
Query is:
SELECT
IMS_BO_PMAN08.REF_ID,( sum(IMS_BO_PMAN08_TRAN.MONTH_13_APR) ) + ( sum(IMS_BO_PMAN08_TRAN.MONTH_14_MAY) ) ,
decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast'),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,'E','Expenditure','U','Unit completions','A','Allocation Takeup','S','SOS units','T','SOS Expenditure','G','Grant Claim Units','H','Larger Homes','C','FC Unit Completions','F','FC Expenditure','V','ACQ Expenditure')
FROM
IMS_BO_PMAN08,
IMS_BO_PMAN08_TRAN
WHERE
( IMS_BO_PMAN08.PROG_MAN_ID=IMS_BO_PMAN08_TRAN.PROG_MAN_ID )
AND ( IMS_BO_PMAN08.VERSION_ID IN (select version_id from ims_bo_version where version_id = 1 ) )
AND ( IMS_BO_PMAN08.INV_REGION_CODE > 2 )
and decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast') ='Actual'
GROUP BY
IMS_BO_PMAN08.REF_ID,decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast'),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,'E','Expenditure','U','Unit completions','A','Allocation Takeup','S','SOS units','T','SOS Expenditure','G','Grant Claim Units','H','Larger Homes','C','FC Unit Completions','F','FC Expenditure','V','ACQ Expenditure');
I am seeing the same execution plan when running the query against either database, with the same cost in each case. However, the physical reads on server B is ten times that of on server A
Server A
=====
293851 rows selected.
Elapsed: 00:00:06.58
Execution Plan
0 SELECT STATEMENT Optimizer=FIRST_ROWS (Cost=50270 Card=27811 Bytes=973385)
1 0 SORT (GROUP BY) (Cost=50270 Card=27811 Bytes=973385)
2 1 HASH JOIN (Cost=50088 Card=27811 Bytes=973385)
3 2 TABLE ACCESS (BY INDEX ROWID) OF 'IMS_BO_PMAN08' (Cost=17990 Card=26243 Bytes=446131)
4 3 INDEX (RANGE SCAN) OF 'IMS_BO_PMAN08_IX1' (UNIQUE) (Cost=105 Card=26243)
5 2 NESTED LOOPS (Cost=32049 Card=107258 Bytes=1930644)
6 5 INDEX (UNIQUE SCAN) OF 'IMS_BO_VERSION_IX1' (UNIQUE)
7 5 TABLE ACCESS (FULL) OF 'IMS_BO_PMAN08_TRAN' (Cost=32048 Card=107258 Bytes=1716128)
Statistics
0 recursive calls
13 db block gets
288529 consistent gets
*18,218 physical reads*
0 redo size
17924295 bytes sent via SQL*Net to client
2174914 bytes received via SQL*Net from client
19592 SQL*Net roundtrips to/from client
0 sorts (memory)
1 sorts (disk)
293851 rows processed
Server B
=====
292677 rows selected.
Elapsed: 00:00:32.66
Execution Plan
0 SELECT STATEMENT Optimizer=FIRST_ROWS (Cost=50255 Card=27805 Bytes=973175)
1 0 SORT (GROUP BY) (Cost=50255 Card=27805 Bytes=973175)
2 1 HASH JOIN (Cost=50073 Card=27805 Bytes=973175)
3 2 TABLE ACCESS (BY INDEX ROWID) OF 'IMS_BO_PMAN08' (Cost=17984 Card=26237 Bytes=446029)
4 3 INDEX (RANGE SCAN) OF 'IMS_BO_PMAN08_IX1' (UNIQUE) (Cost=105 Card=26237)
5 2 NESTED LOOPS (Cost=32040 Card=107230 Bytes=1930140)
6 5 INDEX (UNIQUE SCAN) OF 'IMS_BO_VERSION_IX1' (UNIQUE)
7 5 TABLE ACCESS (FULL) OF 'IMS_BO_PMAN08_TRAN' (Cost=32039 Card=107230 Bytes=1715680)
Statistics
0 recursive calls
357 db block gets
250918 consistent gets
*188,332 physical reads*
0 redo size
17853447 bytes sent via SQL*Net to client
2166145 bytes received via SQL*Net from client
19513 SQL*Net roundtrips to/from client
0 sorts (memory)
1 sorts (disk)
292677 rows processed
8.1.6.3 on solaris 8
Can anyone tell me where the excessive physical i/o's (and presumably associated runtime) is coming from? Any pointers much appreciated.
Pete
Edited by: user12248598 on 17-Mar-2010 09:01

sort_area_size, sort_area_retained_size & hash_area_size are the same size for both instances, as are all NLS settings.
Tables are not specified NOCACHE, and there are no additional buffer pools.
Running with sql_trace enabled for both queries highlighed some very interesting results:
For the slow query, this is the tkprof output, unfortunately waits=yes is not available in 8.1.6
TKPROF: Release 8.1.6.3.0 - Production on Tue Mar 23 14:54:18 2010
(c) Copyright 1999 Oracle Corporation. All rights reserved.
Trace file: imsroc_ora_10166.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
alter session set events '10046 trace name context forever, level 8'
call     count       cpu    elapsed       disk      query    current        rows
Parse        0      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
total        1      0.00       0.00          0          0          0           0
Misses in library cache during parse: 0
Misses in library cache during execute: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5
BEGIN DBMS_APPLICATION_INFO.SET_MODULE(:1,NULL); END;
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.01       0.01          0          0          0           1
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.01       0.01          0          0          0           1
Misses in library cache during parse: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5
SELECT
IMS_BO_PMAN08.REF_ID,
   ( sum(IMS_BO_PMAN08_TRAN.MONTH_13_APR) ) + ( sum(IMS_BO_PMAN08_TRAN.MONTH_14_MAY) ) ,
     decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast'),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,'E','Expenditure','U','Unit completions','A','Allocation Takeup
','S','SOS units','T','SOS Expenditure','G','Grant Claim Units','H','Larger Homes','C','FC Unit Comple
tions','F','FC Expenditure','V','ACQ Expenditure')
FROM
bo_ims.IMS_BO_PMAN08,
bo_ims.IMS_BO_PMAN08_TRAN
WHERE ( IMS_BO_PMAN08.PROG_MAN_ID=IMS_BO_PMAN08_TRAN.PROG_MAN_ID )
AND ( IMS_BO_PMAN08.VERSION_ID IN (select version_id from bo_ims.ims_bo_version where version_id =
1 ) )
    AND ( IMS_BO_PMAN08.INV_REGION_CODE > 2 )
    and decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast') = 'Actual'
GROUP BY
IMS_BO_PMAN08.REF_ID,
    decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast'),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,'E','Expenditure','U','Unit completions','A','Allocation Takeup
','S','SOS units','T','SOS Expenditure','G','Grant Claim Units','H','Larger Homes','C','FC Unit Comple
tions','F','FC Expenditure','V','ACQ Expenditure')
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    16278     15.36      36.39     215625     251560        361      244156
total    16280     15.36      36.39     215625     251560        361      244156
Misses in library cache during parse: 0
Optimizer goal: FIRST_ROWS
Parsing user id: 5
OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS
call     count       cpu    elapsed       disk      query    current        rows
Parse        2      0.00       0.00          0          0          0           0
Execute      3      0.01       0.01          0          0          0           1
Fetch    16278     15.36      36.39     215625     251560        361      244156
total    16283     15.37      36.40     215625     251560        361      244157
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        0      0.00       0.00          0          0          0           0
Execute      0      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
total        0      0.00       0.00          0          0          0           0
Misses in library cache during parse: 0
    3 user SQL statements in session.
    0 internal SQL statements in session.
    3 SQL statements in session.
Trace file: imsroc_ora_10166.trc
Trace file compatibility: 8.00.04
Sort options: default
       2 sessions in tracefile.
       5 user SQL statements in trace file.
       0 internal SQL statements in trace file.
       3 SQL statements in trace file.
       3 unique SQL statements in trace file.
   75998 lines in trace file.And this is the tkprof formatted output for the faster running query:
TKPROF: Release 8.1.6.3.0 - Production on Tue Mar 23 14:56:28 2010
(c) Copyright 1999 Oracle Corporation. All rights reserved.
Trace file: imslive_ora_7489.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
alter session set events '10046 trace name context forever, level 8'
call     count       cpu    elapsed       disk      query    current        rows
Parse        0      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
total        1      0.00       0.00          0          0          0           0
Misses in library cache during parse: 0
Misses in library cache during execute: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5
SELECT
IMS_BO_PMAN08.REF_ID,
   ( sum(IMS_BO_PMAN08_TRAN.MONTH_13_APR) ) + ( sum(IMS_BO_PMAN08_TRAN.MONTH_14_MAY) ) ,
     decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,:SYS_B_00,:SYS_B_01,:SYS_B_02,:SYS_B_03),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,:SYS_B_04,:SYS_B_05,:SYS_B_06,:SYS_B_07,:SYS_B_08,:SYS_B_09,:SYS_B_10,:
SYS_B_11,:SYS_B_12,:SYS_B_13,:SYS_B_14,:SYS_B_15,:SYS_B_16,:SYS_B_17,:SYS_B_18,:SYS_B_19,:SYS_B_20,:SYS_B_21,:
SYS_B_22,:SYS_B_23)
FROM
BO_IMS.IMS_BO_PMAN08,
BO_IMS.IMS_BO_PMAN08_TRAN
WHERE ( IMS_BO_PMAN08.PROG_MAN_ID=IMS_BO_PMAN08_TRAN.PROG_MAN_ID )
AND ( IMS_BO_PMAN08.VERSION_ID IN (select version_id from bo_ims.ims_bo_version where version_id = :SYS_B_
24 ) )
    AND ( IMS_BO_PMAN08.INV_REGION_CODE > :SYS_B_25 )
    and decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,:SYS_B_26,:SYS_B_27,:SYS_B_28,:SYS_B_29) = :SYS_B_30
GROUP BY
IMS_BO_PMAN08.REF_ID,
    decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,:SYS_B_31,:SYS_B_32,:SYS_B_33,:SYS_B_34),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,:SYS_B_35,:SYS_B_36,:SYS_B_37,:SYS_B_38,:SYS_B_39,:SYS_B_40,:SYS_B_41,:
SYS_B_42,:SYS_B_43,:SYS_B_44,:SYS_B_45,:SYS_B_46,:SYS_B_47,:SYS_B_48,:SYS_B_49,:SYS_B_50,:SYS_B_51,:SYS_B_52,:
SYS_B_53,:SYS_B_54)
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      2      0.00       0.00          0          0          0           0
Fetch    20042      0.00       0.00      20064     295221         13      300608
total    20045      0.00       0.00      20064     295221         13      300608
Misses in library cache during parse: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5
Rows     Row Source Operation
300608 SORT GROUP BY
300628   NESTED LOOPS
55647    NESTED LOOPS
      2     INDEX UNIQUE SCAN (object id 151050)
55647     TABLE ACCESS BY INDEX ROWID IMS_BO_PMAN08
55649      INDEX RANGE SCAN (object id 185149)
300628    TABLE ACCESS BY INDEX ROWID IMS_BO_PMAN08_TRAN
356274     INDEX RANGE SCAN (object id 157241)
DELETE FROM PLAN_TABLE
WHERE
STATEMENT_ID=:1
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          3          5         12           0
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          3          5         12           0
Misses in library cache during parse: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5
Rows     Row Source Operation
      1 DELETE PLAN_TABLE
      1   TABLE ACCESS FULL PLAN_TABLE
EXPLAIN PLAN SET STATEMENT_ID='PLUS18028884' FOR SELECT
IMS_BO_PMAN08.REF_ID,
   ( sum(IMS_BO_PMAN08_TRAN.MONTH_13_APR) ) + ( sum(IMS_BO_PMAN08_TRAN.MONTH_14_MAY) ) ,
     decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast'),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,'E','Expenditure','U','Unit completions','A','Allocation Takeup','S','S
OS units','T','SOS Expenditure','G','Grant Claim Units','H','Larger Homes','C','FC Unit Completions','F','FC E
xpenditure','V','ACQ Expenditure')
FROM
BO_IMS.IMS_BO_PMAN08,
BO_IMS.IMS_BO_PMAN08_TRAN
WHERE ( IMS_BO_PMAN08.PROG_MAN_ID=IMS_BO_PMAN08_TRAN.PROG_MAN_ID )
AND ( IMS_BO_PMAN08.VERSION_ID IN (select version_id from bo_ims.ims_bo_version where version_id = 1 ) )
    AND ( IMS_BO_PMAN08.INV_REGION_CODE > 2 )
    and decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast') = 'Actual'
GROUP BY
IMS_BO_PMAN08.REF_ID,
    decode(IMS_BO_PMAN08_TRAN.TRANS_SUB_TYPE,'A','Actual','F','Forecast'),
decode(IMS_BO_PMAN08_TRAN.TRANS_TYPE,'E','Expenditure','U','Unit completions','A','Allocation Takeup','S','S
OS units','T','SOS Expenditure','G','Grant Claim Units','H','Larger Homes','C','FC Unit Completions','F','FC E
xpenditure','V','ACQ Expenditure')
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      0      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
total        1      0.00       0.00          0          0          0           0
Misses in library cache during parse: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5
insert into plan_table (statement_id, timestamp, operation, options,
object_node, object_owner, object_name, object_instance, object_type,
search_columns, id, parent_id, position, other,optimizer, cost, cardinality,
   bytes, other_tag, partition_start, partition_stop, partition_id,
distribution )
values
(:1,SYSDATE,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,:15,:16,:17,:18,:19,
:20,:21,:22)
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      7      0.00       0.00          1          3          9           7
Fetch        0      0.00       0.00          0          0          0           0
total        8      0.00       0.00          1          3          9           7
Misses in library cache during parse: 1
Optimizer goal: FIRST_ROWS
Parsing user id: 5     (recursive depth: 1)
select o.name, u.name
from
sys.obj$ o, sys.user$ u where obj# = :1and owner# = user#
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      2      0.00       0.00          0          0          0           0
Fetch        2      0.00       0.00          3         12          0           2
total        5      0.00       0.00          3         12          0           2
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: SYS   (recursive depth: 1)
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      4      0.00       0.00          3          5         12           0
Fetch    20042      0.00       0.00      20064     295221         13      300608
total    20049      0.00       0.00      20067     295226         25      300608
Misses in library cache during parse: 3
Misses in library cache during execute: 1
OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS
call     count       cpu    elapsed       disk      query    current        rows
Parse        2      0.00       0.00          0          0          0           0
Execute      9      0.00       0.00          1          3          9           7
Fetch        2      0.00       0.00          3         12          0           2
total       13      0.00       0.00          4         15          9           9
Misses in library cache during parse: 2
    5 user SQL statements in session.
    1 internal SQL statements in session.
    6 SQL statements in session.
Trace file: imslive_ora_7489.trc
Trace file compatibility: 8.00.04
Sort options: default
       3 sessions in tracefile.
       8 user SQL statements in trace file.
       1 internal SQL statements in trace file.
       6 SQL statements in trace file.
       6 unique SQL statements in trace file.
   77410 lines in trace file.The sql statement as run did not make use of bind variables, so the ones in the tkprof output for the longer running statement made me immediately think of cursor sharing, and right there in the init.ora for the faster running database was CURSOR_SHARING=FORCE.
I'm not familiar with the history of the databases, nor the specific reasoning for enabling cursor sharing (bind variable usage seems prevalent in all custom code) so I've replicated the setting on the slower database, resulting in a similar tkprof output to the faster server, with a runtime of 7 seconds for 2nd and subsequent runs.
My immediate issue is now solved, thanks to all who contributed, and apologies for not spotting the obvious earlier.
Regards, Pete

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Fetch        0      0.00       0.00          0          0          0           0
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Parsing user id: 22
Elapsed times include waiting on following events:
Event waited on                             Times   Max. Wait Total Waited
----------------------------------------   Waited ---------- ------------
latch: row cache objects                        1        0.00          0.00
log file sync                                   1        0.00          0.00
SQL*Net message to client                       1        0.00          0.00
SQL*Net message from client                     1        0.00          0.00
********************************************************************************

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AS ACA_FCA, DECODE(MRH_RESI_STATUS,'I',MRH_PROF_ADDR_LINE_1,'A',
MRH_RES_ADDR_LINE_1) AS L_ADD1, DECODE(MRH_RESI_STATUS,'I',MRH_Pexplain plan
SQL> explain plan for select MRH_MRN,DECODE(MRH_SEX,'M','MALE','FEMALE') AS SEX
, trim((mrh_sur_name||' '||mrh_first_name||' '||mrh_middle_name)) as MEMNAME, de
code(nvl(mrh_fellow_status_yn,'333'),'Y','FCA','ACA')AS ACA_FCA, DECODE(MRH_RESI
_STATUS,'I',MRH_PROF_ADDR_LINE_1,'A',
2 MRH_RES_ADDR_LINE_1) AS L_ADD1, DECODE(MRH_RESI_STATUS,'I',MRH_PROF_ADDR_LI
NE_2,'A',MRH_RES_ADDR_LINE_2) AS L_ADD2, DECODE(MRH_RESI_STATUS,'I',MRH_PROF_ADD
R_LINE_3,'A',MRH_RES_ADDR_LINE_3) ASL_ADD3, DECODE(MRH_RESI_STATUS,'I',MRH_PROF_
ADDR_LINE_4,'A',
3 MRH_RES_ADDR_LINE_4) AS L_ADD4, DECODE(MRH_RESI_STATUS,'I',a.city_name,'A',
C.CITY_NAME) AS L_CITY, DECODE(MRH_RESI_STATUS,'I',MRH_PROF_ZIP_POSTAL_CODE,'A',
MRH_RES_ZIP_POSTAL_CODE) AS L_PIN, DECODE(MRH_RESI_STATUS,'I',b.cou_name,'A',D.C
OU_NAME) as L_Country,
4 DECODE(MRH_RESI_STATUS,'I','NOT APPLICABLE',MRH_PROF_ADDR_LINE_1)AS R_ADD1,
DECODE(MRH_RESI_STATUS,'I',' ',MRH_PROF_ADDR_LINE_2)AS R_ADD2, DECODE(MRH_RESI_
STATUS,'I',' ',MRH_PROF_ADDR_LINE_3)
5 AS R_ADD3, DECODE(MRH_RESI_STATUS,'I',' ',MRH_PROF_ADDR_LINE_4)AS R_ADD4, D
ECODE(MRH_RESI_STATUS,'I',' ','A',A.CITY_NAME) AS R_CITY, DECODE(MRH_RESI_STATUS
,'I',' ','A',MRH_PROF_ZIP_POSTAL_CODE) AS R_PIN, DECODE(MRH_RESI_STATUS,'I',' ',
'A',B.COU_NAME) as
6 R_Country, decode(nvl(mrh_mem_sub_status,'555'),'26','EXPIRED','') as sub_s
tatus, decode(nvl(mrh_mem_status,'777'),'1','ACTIVE','2','REMOVED') as mem_statu
s,mrh_resi_status, DECODE(MRH_COP_STATUS,'1',DECODE(MRH_COP_TYPE ,'13','FULLTIME
-COP','1',
7 'FULLTIME-COP', '12','PARTTIME-COP','2','PARTTIME-COP'),'NOT HOLDING COP')
AS COP_STATUS, TO_CHAR(MRH_ENROL_DT,'RRRR') AS ASSO_YR,TO_CHAR(MRH_FELLOW_DT,'RR
RR') AS FELLOW_YR from om_mem_reg_head,om_city A,
8 om_country B,om_city C,om_country D where mrh_doc_status=5 and mrh_prof_
city_code=A.City_code(+) and mrh_prof_cou_code=B.cou_code(+) and mrh_res_city_c
ode=C.City_code(+) and mrh_res_cou_code=D.cou_code(+) and trim((mrh_sur_name||'
'||mrh_first_name||
9 ''||mrh_middle_name)) like upper('%%') ORDER BY trim((mrh_sur_name||' '||m
rh_first_name||' '||mrh_middle_name))
10 ;
Explained.
SQL> select * from table(dbms_xplan.displaY());
PLAN_TABLE_OUTPUT
| Id | Operation              | Name            | Rows | Bytes |TempSpc| Cost
|
|   0 | SELECT STATEMENT       |                  | 2870 |   762K|       | 202
PLAN_TABLE_OUTPUT
8 |
|   1 | SORT ORDER BY         |                  | 2870 |   762K| 1592K| 202
8 |
|   2 |   NESTED LOOPS OUTER   |                  | 2870 |   762K|       | 190
2 |
|   3 |    NESTED LOOPS OUTER |                  | 2870 |   714K|       | 190
2 |
PLAN_TABLE_OUTPUT
|   4 |     HASH JOIN OUTER    |                  | 2870 |   667K|       | 190
2 |
|   5 |      HASH JOIN OUTER   |                  | 2870 |   616K|       | 189
2 |
|   6 |       TABLE ACCESS FULL| OM_MEM_REG_HEAD | 2870 |   566K|       | 188
2 |
|   7 |       TABLE ACCESS FULL| OM_COUNTRY       |   677 | 12186 |       |
4 |
PLAN_TABLE_OUTPUT
|   8 |      TABLE ACCESS FULL | OM_COUNTRY       |   677 | 12186 |       |
4 |
|   9 |     INDEX UNIQUE SCAN | CITY_CODE_PK     |     1 |    17 |       |
|
| 10 |    INDEX UNIQUE SCAN   | CITY_CODE_PK     |     1 |    17 |       |
|
PLAN_TABLE_OUTPUT
Note: cpu costing is off, PLAN_TABLE' is old version
18 rows selected.
SQL>Please suggest me whjat cab done to overcome the same
Edited by: user00726 on Feb 3, 2009 5:03 AM

SQL> show arraysize
arraysize 15
SQL>should i set SDU parameter in tnsnames and listener.ora
for more info related to the same...pls do visit the below thread:
n/w perfromance related problem

Query tuning-how to reduce physical reads-help me

1* select * from masterbillingInvoiceview Where SiteIID =300964 and InvoiceID like '%' order by Invoice asc
SQL> /
33 rows selected.
Elapsed: 00:00:00.34
Execution Plan
Plan hash value: 352896138
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 16 | 6304 | 341 (3)| 00:00:05 |
| 1 | SORT ORDER BY | | 16 | 6304 | 341 (3)| 00:00:05 |
| 2 | TABLE ACCESS BY INDEX ROWID | ADDRESS | 1 | 48 | 2 (0)| 00:00:01
| 3 | NESTED LOOPS | | 16 | 6304 | 340 (3)| 00:00:05 |
| 4 | NESTED LOOPS | | 16 | 5536 | 316 (3)| 00:00:04 |
|* 5 | HASH JOIN OUTER | | 16 | 5168 | 308 (3)| 00:00:04 |
|* 6 | HASH JOIN | | 16 | 4992 | 302 (3)| 00:00:04 |
|* 7 | HASH JOIN | | 16 | 4752 | 298 (3)| 00:00:04 |
| 8 | NESTED LOOPS | | 17 | 4828 | 44 (0)| 00:00:01 |
| 9 | NESTED LOOPS | | 17 | 3451 | 35 (0)| 00:00:01 |
| 10 | NESTED LOOPS OUTER | | 1 | 91 | 2 (0)| 00:00:01 |
| 11 | TABLE ACCESS BY INDEX ROWID| SITEMASTER | 1 | 74 | 1 (0)| 00:00:01 |
|* 12 | INDEX UNIQUE SCAN | PK_SITEMASTER | 1 | | 1 (0)| 00:00:01 |
| 13 | TABLE ACCESS BY INDEX ROWID| INVGROUPS | 1735 | 29495 | 1 (0)| 00:00:01 |
|* 14 | INDEX UNIQUE SCAN | PK_INVGROUPS | 1 | | 1 (0)| 00:00:01 |
|* 15 | TABLE ACCESS BY INDEX ROWID | INVOICEHEAD | 17 | 1904 | 33 (0)| 00:00:01 |
|* 16 | INDEX RANGE SCAN | IDX_INVOICEHEADSITEIID | 271 | | 1 (0)| 00:00:01 |
| 17 | TABLE ACCESS BY INDEX ROWID | CUSTOMER | 1 | 81 | 1 (0)| 00:00:01 |
|* 18 | INDEX UNIQUE SCAN | PK_CUSTOMER | 1 | | 1 (0)| 00:00:01 |
| 19 | VIEW | | 35844 | 455K| 254 (3)| 00:00:04 |
| 20 | HASH GROUP BY | | 35844 | 455K| 254 (3)| 00:00:04 |
| 21 | TABLE ACCESS FULL | CONTACT | 56100 | 712K| 250 (1)| 00:00:03 |
| 22 | VIEW | index$_join$_009 | 7 | 105 | 3 (0)| 00:00:01 |
|* 23 | HASH JOIN | | | | | |
| 24 | INDEX FAST FULL SCAN | IDX_PAYMENTTERMSID | 7 | 105 | 1 (0)| 00:00:01
| 25 | INDEX FAST FULL SCAN | PK_PAYMENTTERMS | 7 | 105 | 1 (0)| 00:00:01
| 26 | VIEW | index$_join$_011 | 1428 | 15708 | 6 (0)| 00:00:01 |
|* 27 | HASH JOIN | | | | | |
| 28 | INDEX FAST FULL SCAN | PK_EMPLOYEE | 1428 | 15708 | 3 (0)| 00:00:01 |
| 29 | INDEX FAST FULL SCAN | IDX_EMPLOYEEEMPLOYEEID | 1428 | 15708 | 3 (0)| 00:00:01
| 30 | TABLE ACCESS BY INDEX ROWID | CONTACT | 1 | 23 | 1 (0)| 00:00:
|* 31 | INDEX UNIQUE SCAN | PK_CONTACT | 1 | | 1 (0)| 00:00:01 |
|* 32 | INDEX RANGE SCAN | PK_ADDRESS | 1 | | 1 (0)| 00:00:01 |
Predicate Information (identified by operation id):
5 - access("A"."CREATEDBY"="J"."EMPIID"(+))
6 - access("A"."TERMSIID"="H"."PAYMENTTERMSIID")
7 - access("D"."CUSTOMERIID"="F"."CUSTOMERIID")
12 - access("B"."SITEIID"=300964)
14 - access("B"."PARENTIID"="I"."GROUPIID"(+))
15 - filter("A"."TYPE"=4 AND "A"."INVOICEID" LIKE '%')
16 - access("A"."SITEIID"=300964)
18 - access("A"."BILLINGCUSTOMERIID"="D"."CUSTOMERIID")
23 - access(ROWID=ROWID)
27 - access(ROWID=ROWID)
31 - access("F"."CONTACTIID"="G"."CONTACTIID")
32 - access("E"."ADDRESSIID"=NVL("D"."BILLINGADDRESSIID","D"."ADDRESSIID"))
Statistics
107 recursive calls
0 db block gets
2819 consistent gets
0 physical reads
0 redo size
6586 bytes sent via SQL*Net to client
356 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
33 rows processed
SQL> ed
Wrote file afiedt.buf
1* select * from masterbillingInvoiceview Where SiteIID =300964 and InvoiceID like '%%%' order by Invoice asc
SQL> /
33 rows selected.
Elapsed: 00:06:15.23
Execution Plan
Plan hash value: 1828716447
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 2 | 964 | 295 (3)| 00:00:04 |
|* 1 | FILTER | | | | | |
| 2 | SORT GROUP BY | | 2 | 964 | 295 (3)| 00:00:04 |
| 3 | MERGE JOIN CARTESIAN | | 72315 | 33M| 291 (1)| 00:00:04 |
| 4 | TABLE ACCESS BY INDEX ROWID | ADDRESS | 1 | 52 | 2 (0)| 00:00:01 |
| 5 | NESTED LOOPS | | 1 | 447 | 41 (0)| 00:00:01 |
| 6 | NESTED LOOPS | | 1 | 395 | 40 (0)| 00:00:01 |
| 7 | NESTED LOOPS | | 1 | 382 | 38 (0)| 00:00:01 |
| 8 | NESTED LOOPS OUTER | | 1 | 289 | 37 (0)| 00:00:01 |
| 9 | NESTED LOOPS | | 1 | 266 | 36 (0)| 00:00:01 |
| 10 | NESTED LOOPS | | 1 | 239 | 35 (0)| 00:00:01 |
| 11 | NESTED LOOPS OUTER | | 1 | 115 | 2 (0)| 00:00:01 |
| 12 | TABLE ACCESS BY INDEX ROWID| SITEMASTER | 1 | 86 | 1 (0)| 00:00:01 |
|* 13 | INDEX UNIQUE SCAN | PK_SITEMASTER | 1 | | 1 (0)| 00:00:01 |
| 14 | TABLE ACCESS BY INDEX ROWID| INVGROUPS | 1735 | 50315 | 1 (0)| 00:00:01 |
|* 15 | INDEX UNIQUE SCAN | PK_INVGROUPS | 1 | | 1 (0)| 00:00:01 |
|* 16 | TABLE ACCESS BY INDEX ROWID | INVOICEHEAD | 1 | 124 | 33 (0)| 00:00:01 |
|* 17 | INDEX RANGE SCAN | IDX_INVOICEHEADSITEIID | 271 | | 1 (0)| 00:00:01 |
| 18 | TABLE ACCESS BY INDEX ROWID | PAYMENTTERMS | 1 | 27 | 1 (0)| 00:00:01 |
|* 19 | INDEX UNIQUE SCAN | PK_PAYMENTTERMS | 1 | | 1 (0)| 00:00:01 |
| 20 | TABLE ACCESS BY INDEX ROWID | EMPLOYEE | 1 | 23 | 1 (0)| 00:00:01 |
|* 21 | INDEX UNIQUE SCAN | PK_EMPLOYEE | 1 | | 1 (0)| 00:00:01 |
| 22 | TABLE ACCESS BY INDEX ROWID | CUSTOMER | 1 | 93 | 1 (0)| 00:00:01 |
|* 23 | INDEX UNIQUE SCAN | PK_CUSTOMER | 1 | | 1 (0)| 00:00:01 |
| 24 | TABLE ACCESS BY INDEX ROWID | CONTACT | 1 | 13 | 2 (0)| 00:00:01 |
|* 25 | INDEX RANGE SCAN | IDX_CONTACTCUSTOMERIID | 2 | | 1 (0)| 00:00:01 |
|* 26 | INDEX RANGE SCAN | PK_ADDRESS | 1 | | 1 (0)| 00:00:01 |
| 27 | BUFFER SORT | | 56100 | 1917K| 294 (3)| 00:00:04 |
| 28 | TABLE ACCESS FULL | CONTACT | 56100 | 1917K| 250 (1)| 00:00:03 |
Predicate Information (identified by operation id):
1 - filter("G"."CONTACTIID"=MAX("CONTACTIID"))
13 - access("B"."SITEIID"=300964)
15 - access("B"."PARENTIID"="I"."GROUPIID"(+))
16 - filter("A"."TYPE"=4 AND "A"."INVOICEID" LIKE '%%%')
17 - access("A"."SITEIID"=300964)
19 - access("A"."TERMSIID"="H"."PAYMENTTERMSIID")
21 - access("A"."CREATEDBY"="J"."EMPIID"(+))
23 - access("A"."BILLINGCUSTOMERIID"="D"."CUSTOMERIID")
25 - access("D"."CUSTOMERIID"="CUSTOMERIID")
filter("CUSTOMERIID" IS NOT NULL)
26 - access("E"."ADDRESSIID"=NVL("D"."BILLINGADDRESSIID","D"."ADDRESSIID"))
Statistics
1952 recursive calls
78 db block gets
4649 consistent gets
236151 physical reads
0 redo size
6586 bytes sent via SQL*Net to client
356 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
1 sorts (memory)
1 sorts (disk)
33 rows processed
this is the execution plan of my one query with a small difference, bt there is large diffference in physical reads..
can anyone help me out of this
thanks
aju

Hi,
Can you please format your explain plan using
{ code } --without space
Explain plan
{ code } -- without any space
What is your DB version?
There are differences in access and filter criteria...
-- FRIST QUERY
5 - access("A"."CREATEDBY"="J"."EMPIID"(+))
6 - access("A"."TERMSIID"="H"."PAYMENTTERMSIID")
7 - access("D"."CUSTOMERIID"="F"."CUSTOMERIID")
12 - access("B"."SITEIID"=300964)
14 - access("B"."PARENTIID"="I"."GROUPIID"(+))
15 - filter("A"."TYPE"=4 AND "A"."INVOICEID" LIKE '%')
16 - access("A"."SITEIID"=300964)
18 - access("A"."BILLINGCUSTOMERIID"="D"."CUSTOMERIID")
23 - access(ROWID=ROWID)
27 - access(ROWID=ROWID)
31 - access("F"."CONTACTIID"="G"."CONTACTIID")
32 - access("E"."ADDRESSIID"=NVL("D"."BILLINGADDRESSIID","D"."ADDRESSIID"))
------SECOND QUERY
1 - filter("G"."CONTACTIID"=MAX("CONTACTIID"))
13 - access("B"."SITEIID"=300964)
15 - access("B"."PARENTIID"="I"."GROUPIID"(+))
16 - filter("A"."TYPE"=4 AND "A"."INVOICEID" LIKE '%%%')
17 - access("A"."SITEIID"=300964)
19 - access("A"."TERMSIID"="H"."PAYMENTTERMSIID")
21 - access("A"."CREATEDBY"="J"."EMPIID"(+))
23 - access("A"."BILLINGCUSTOMERIID"="D"."CUSTOMERIID")
25 - access("D"."CUSTOMERIID"="CUSTOMERIID")
filter("CUSTOMERIID" IS NOT NULL)
26 - access("E"."ADDRESSIID"=NVL("D"."BILLINGADDRESSIID","D"."ADDRESSIID"))-Avinash

Oracle 9i Performance Issue High Physical Reads

Dear All,
I have Oracle 9i Release 9.2.0.5.0 database under HP Unix, I have run the query and got following output. Can any body just have a look and advise what to do in the following situation? We have performance issues.
Many thanks in advance
Buffer Pool Advisory for DB: DBPR Instance: DBPR End Snap: 902
-> Only rows with estimated physical reads >0 are displayed
Size for Size Buffers for Est Physical Estimated
P Estimate (M) Factr Estimate Read Factor Physical Reads
D 416 .1 51,610 4.27 1,185,670,652
D 832 .2 103,220 2.97 825,437,374
D 1,248 .3 154,830 2.03 563,139,985
D 1,664 .4 206,440 1.49 412,550,232
D 2,080 .5 258,050 1.32 366,745,510
D 2,496 .6 309,660 1.23 340,820,773
D 2,912 .7 361,270 1.14 317,544,771
D 3,328 .8 412,880 1.09 301,680,173
D 3,744 .9 464,490 1.04 288,191,418
D 4,096 1.0 508,160 1.00 276,929,627

Hi,
Actually you didnt give the exact problem statement.
Seems to be your database is I/O bound. Ok, do the following one by one:
1. Identify the FTS queries and try to create the optimal indexes (depending on the disk reads factor!!) on the problem queries.
2. To reduce the 276M physical reads, you need to allocate more memory to db_cache_size. try 8GB (initially) and then depending on the buffer advisery you can increase further if you have more memory on the box.
3. as a Next step , configure KEEP and RECYCLE cache to get the benefits of reduced I/O by multiple pools. Allocate objects to the KEEP/RECYCLE pools.
Thanks,

Hint or parameter to force physical read

I am using Oracle 11.2.0.3. I have a query which took 45 minute the first time and it take 4 minutes in subsequent run in QC environment. In both the cases it uses same plan. If I try the query again in few days , first time it takes considerable amount of time.Most of the wait is in range index scan - 'db file parallel read'
Same query runs within 2 minutes in lower environment with different plan. I have used hint to make the plan same in QC environment. Now query runs as expected but I suspect it might slow down if the data is not cached. I do not have access to alter system flush buffer cache privilege.
Is there any hint or parameter I can use force physical read?
Which view will tell me if a table is still cached in memory?

spur230 wrote:
<snip>
Which view will tell me if a table is still cached in memory?
v$bh will tell you what blocks of an object are cached:
orcla> select file#,block#,status from v$bh where objd=(select data_object_id
2 from dba_objects where owner='SCOTT' and objecT_name='DEPT');
no rows selected
orcla> select * from scott.dept;
    DEPTNO DNAME          LOC
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
orcla> select file#,block#,status from v$bh where objd=(select data_object_id
2 from dba_objects where owner='SCOTT' and objecT_name='DEPT');
     FILE#     BLOCK# STATUS
         4        131 xcur
         4        134 xcur
         4        132 xcur
         4        135 xcur
         4        130 xcur
         4        133 xcur
6 rows selected.
orcla>
but you do need to be aware of the status. There may be several versions of a block cached.

No of physical reads of buffers from disk on PROD and Clone has huge differ

Please help !
I am having a problem interpreting a tkprof report.
I am executing the same statement below in PROD and Clone of PROD.
What I do not understand why the tkprof report shows huge difference in disk reads for same executions from PROD and Clone of PROD. I.e. first execution disk reads = 757187 , second = 6.
I expected to see Similar disk reads in the second execution also.The data it fetches is same in both the Instances.
Statment
SELECT NVL(SUM(RG_OTH.DEBIT),0),NVL(SUM(RG_OTH.CREDIT),0)
FROM
JA_IN_PLA PLA,JAI_RG_OTHERS RG_OTH,HR_ALL_ORGANIZATION_UNITS HOU,
HR_LOCATIONS LOC,JA_IN_HR_ORGANIZATION_UNITS HR_ORG WHERE 1 = 1 AND
PLA.ORGANIZATION_ID = :b1 AND TRUNC(PLA.CREATION_DATE) >= :b2 AND
TRUNC(PLA.CREATION_DATE) <= :b3 AND HOU.ORGANIZATION_ID =
PLA.ORGANIZATION_ID AND LOC.LOCATION_ID = PLA.LOCATION_ID AND
HR_ORG.ORGANIZATION_ID = PLA.ORGANIZATION_ID AND HR_ORG.LOCATION_ID =
PLA.LOCATION_ID AND TRANSACTION_ID = 19 AND INVENTORY_ITEM_ID != 0 AND
NVL(ROUNDING_ID,1) != -1 AND RG_OTH.SOURCE_REGISTER_ID = PLA.REGISTER_ID
AND RG_OTH.SOURCE_REGISTER = 'PLA' AND RG_OTH.TAX_TYPE IN (
'EXCISE_EDUCATION_CESS' )
Tkproff from PROD.
call count cpu elapsed disk query current rows
Parse 1 0.01 0.01 0 0 0 0
Execute 1 0.04 0.03 0 0 0 0
Fetch 1 973.41 1724.95 757187 789442 0 1
total 3 973.46 1725.01 757187 789442 0 1
Tkproff from CLONE of PROD.
call count cpu elapsed disk query current rows
Parse 1 0.06 0.05 1 789 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 1 0.73 0.72 6 30594 0 1
total 3 0.79 0.78 7 31383 0 1

wins wrote:
SELECT NVL(SUM(RG_OTH.DEBIT),0),NVL(SUM(RG_OTH.CREDIT),0)
FROM
JA_IN_PLA PLA,JAI_RG_OTHERS RG_OTH,HR_ALL_ORGANIZATION_UNITS HOU,
HR_LOCATIONS LOC,JA_IN_HR_ORGANIZATION_UNITS HR_ORG WHERE 1 = 1 AND
PLA.ORGANIZATION_ID = :b1 AND TRUNC(PLA.CREATION_DATE) >= :b2 AND
TRUNC(PLA.CREATION_DATE) <= :b3 AND HOU.ORGANIZATION_ID =
PLA.ORGANIZATION_ID AND LOC.LOCATION_ID = PLA.LOCATION_ID AND
HR_ORG.ORGANIZATION_ID = PLA.ORGANIZATION_ID AND HR_ORG.LOCATION_ID =
PLA.LOCATION_ID AND TRANSACTION_ID = 19 AND INVENTORY_ITEM_ID != 0 AND
NVL(ROUNDING_ID,1) != -1 AND RG_OTH.SOURCE_REGISTER_ID = PLA.REGISTER_ID
AND RG_OTH.SOURCE_REGISTER = 'PLA' AND RG_OTH.TAX_TYPE IN (
'EXCISE_EDUCATION_CESS' )
Tkproff from PROD.
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.01       0.01          0          0          0           0
Execute      1      0.04       0.03          0          0          0           0
Fetch        1    973.41    1724.95     757187     789442          0           1
total        3    973.46    1725.01     757187     789442          0           1
Tkproff from CLONE of PROD.
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.06       0.05          1        789          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        1      0.73       0.72          6      30594          0           1
total        3      0.79       0.78          7      31383          0           1
As others have pointed out, this looks like a change in execution plan. At a guess, the PROD database is doing a tablescan somewhere (physical reads is approximately equal to logical reads is a pointer).
There are many reasons why this could happen, continuing with the guesswork - we note that the statement was re-optimised (hard parsed) in the clone, but used an existing cursor in production (logical I/O = 0 in prod, 789 in clone). So the plan you got in the clone was the one that Oracle thought best for the inputs you had supplied. The plan in prod could have been produced as the response to a completely different set of input; since you have two bind variables applied to a range based predicated and one bind variable with equality it's possible that you have a histogram that makes a difference on the equality column, alternatively the range of dates used to generate the original plan was very different from the range used in the test.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
Author: <b><em>Oracle Core</em></b>

Logical reads VS physical reads

hello all,
What is the difference between logical reads and physical read ??? I do get the part of logical read (from buffer) and physical read(from disk). And also do know physical reads are bad, but is it true in oracle world..logical reads are bad ??? if so why ??? Could you please explain which on to look for. As i am going thru AWR report and i see segemts by logical/physical read.

The first and foremost difference is that physcial reads are done from the hard disk. And this is always going tobe slwoer than the memory. That's why its said that the physcial ios must be removed. Logical ios are good as they are done from the memory.The theory that logical are also not good is because the logical ios require the access given by latches. So with lots of the gets for the latches put them in to contention and latch contention would make the access to the logical io slower.So its better to do this in less IO even they are logical too.
Lots of logical IOs probably mean that you are accessing unnecessary data which may be not required.
HTH
Aman....

Corruption Parameters Increase High Physical Read for one query

Hi Oracle Experts,
Here is what I am currently facing in my non-prod environment:
We are testing out corruption parameters in non-prod environment and doing a perf test for them and we found that one SELECT query has seen significant decreases in performance; What I mean by that is after adding corruption parameters query is executing 40 sec compare to 18 sec and less. Also, this query is widely use by user in Prod environment, so performance degradation will create serious impact on their work.
I have generated AWR Diff for baseline and perf test following are parameter we have set for corruption test:
db_block_checking (Baseline) LOW (Perftest) MEDIUM
db_block_checksum (Baseline) TRUE (Perftest) FULL
Load Profile from AWR Diff are below:
Load Profile
1st Per Sec 2nd Per Sec %Diff 1st Per Txn 2nd Per Txn %Diff
Redo size: 758,356.06 752,760.94 -0.74 67,161.76 66,631.71 -0.79
Logical reads: 104,637.62 108,677.76 3.86 9,266.95 9,619.77 3.81
Block changes: 1,578.11 1,560.15 -1.14 139.76 139.76 0.00
Physical reads: 103.78 544.41 424.58 9.19 48.19 424.37
Physical writes: 108.94 107.13 -1.66 9.65 9.48 -1.76
User calls: 3,477.02 3,497.26 0.58 307.93 309.57 0.53
Parses: 948.36 949.61 0.13 83.99 84.06 0.08
Hard parses: 0.79 0.54 -31.65 0.07 0.05 -28.57
Sorts: 121.48 120.32 -0.95 10.76 10.65 -1.02
Logons: 0.36 0.27 -25.00 0.03 0.02 -33.33
Executes: 1,575.55 1,591.40 1.01 139.53 140.87 0.96
Transactions: 11.29 11.30 0.09
If we gather stats for tables involved in the query than it performs well in fact with in 5 Sec, but I believe in prod we can't gather state very often.
Questions:
1) How to remedy this situation and have query perform well along with corruption parameters?
2) Does corruption parameters have impact on SELECT query too, I believe it will have impact on INSERT and UPDATE.
3) Any reference to Doc will be highly appreciated.

1) How to remedy this situation and have query perform well along with corruption parameters?Use faster CPU. Checksum is a thing that needs to be computed.
2) Does corruption parameters have impact on SELECT query too, I believe it will have impact on INSERT and UPDATE.According to docs corruption parameters do not have impact on SELECT queries.
However, I believe, checksum has to be recomputed after delayed block cleanout that may be done by SELECT query after big update. ( http://jonathanlewis.wordpress.com/2009/06/16/clean-it-up/ )
3) Any reference to Doc will be highly appreciated.
Why is it difficult for you to find the docs yourself?

High user input output (I/O) and physical reads

Hi guys
Recently we have noticed that our database performance degraded significantly. as we looked around in grid control we noticed that the user IO and Physical reads are really high which cause the database to be laggy.
at first we thought it was memory problem, so we added 2gb to sga. we have set sga to be automatic and it's been like this for the past 2 years.
how do i trouble shoot this problem. i haven't found any troubleshooting guide for it yet.
please instruct me on how to solve it
database: 10.2.0.4 sparc
regards
Sina

Top 5 Timed events
db file sequential read          23,582          679          29          46.3     User I/O
CPU time                                        626                    42.7
db file scattered read     3,089     70     23     4.8     User I/O
db file parallel write     3,478     28     8     1.9     System I/O
log file parallel write     4,201     24     6     1.7     System I/O
SGA Memory Summary
SGA regions     Begin Size (Bytes)     End Size (Bytes) (if different)
Database Buffers     2,768,240,640     2,835,349,504
Fixed Size     2,050,240
Redo Buffers     14,721,024
Variable Size     3,657,439,040     3,590,330,176
Process Memory Summary
     Category     Alloc (MB)     Used (MB)     Avg Alloc (MB)     Std Dev Alloc (MB)     Max Alloc (MB)     Hist Max Alloc (MB)     Num Proc     Num Alloc
B     Other     569.22     0     2.62     3.14     22     24     217     217
     Freeable     101.63     0.00     0.77     0.45     3          132     132
     SQL     91.51     45.35     0.44     0.76     4     78     209     192
     PL/SQL     12.50     5.57     0.06     0.07     0     4     217     217
     JAVA     5.40     5.38     1.08     0.09     1     2     5     5
E     Other     603.20          3.03     3.62     22     24     199     199
     SQL     115.21     64.78     0.60     1.67     21     78     191     182
     Freeable     112.31     0.00     0.83     0.43     3          135     135
     PL/SQL     13.89     5.94     0.07     0.12     1     4     199     199
     JAVA     8.93     8.89     1.12     0.23     2     2
for some reason i can't paste a table into this post but if you want i can email you above tables

No physical reads, plenty of consistant gets

Hi All,
Oracle v11.2 on Linux.
Please have a look at the query I ran and the output. The SQL_ID is of a SELECT command.
What does this situation represents, where there are zero physical reads and plenty of consistant gets ?
For consistant gets, we do read undo information (correct ??), if that undo is read from disk, will that be a "physical read"? i.e. if we read disks for consistant gets, will that be counted under physical reads or not ?
How can I describe the exact data retrival of the command here? Is it the case of "everything it needs is found in the buffer cache" ?
select a.sid, a.value , B.NAME , s.sql_id
from v$sesstat a, v$statname b, v$session s
where A.STATISTIC# = B.STATISTIC#
and b.name in ( 'redo size','physical read bytes','physical reads cache','consistent gets' )
and a.sid = s.sid
and a.sid=1018
order by a.sid;
       SID      VALUE NAME                                                             SQL_ID
      1018    7281396 consistent gets                                                  434u36htuz0s9
      1018          0 physical reads cache                                             434u36htuz0s9
      1018          0 physical read bytes                                              434u36htuz0s9
      1018       4448 redo size                                                        434u36htuz0s9
4 rows selected.Thanks in advance.

>
There are no physical reads, so weather its doing consistant-gets or not, can I say, all data required for the SELECT was in buffer cache ?
>
The data for those system views is cached in memory so Oracle does not read the disk (except at startup) to gather the information.
Some static information, like dictionary objects, is stored stored on disk in the system tablespace but this data is read when the database is mounted and stored in memory structures.
Other dynamic information, like session info, is only stored in memory structures (similar to C arrays) and Oracle can query these as if they were tables.
So no, the data was not in the buffer cache. It was already in system memory.

Unable to reduce Physical Reads

Hi
Problem:
Need to reduce the Physical reads in Oracle 8.1.7
Information:
Optimizer_mode= Choose
Statistics will not be gathered.
Intially the cache hit ratio is 18%. At this point when we checked the SQL Statement
SELECT a32,
F_DOCNUMBER,NVL(a109,'BIWS') AS WorkFlow,
a147 AS Service_Subsidary,
a89 AS StaffInd,
a88 AS SubsidiaryInd
FROM doctaba
WHERE a94 = 'CCOC_CARDS_CCA_060824_6'
AND a40 IN ('3','4','5')
0 recursive calls
81 db block gets
5020 consistent gets
3909 physical reads
0 redo size
401 bytes sent via SQL*Net to client
311 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed.
Once we increase the Buffer Cache Hit Ratio to 90% We got the following
0 recursive calls
81 db block gets
3717 consistent gets
3576 physical reads
0 redo size
401 bytes sent via SQL*Net to client
311 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed.
But can you please advice how to reduce the Physical Reads further.
Note: Table DOCTABA is a Snapshot that is present in Other Database.
Please advice!!
Cheers
Ramkannan.A

Buffer hit cache ratios are totally meaningless as was proven many years ago by Connor's brilliant little utility that allows you to dial in any ratio you want.
The reason your are getting FTEs is because your totally antiquated version of the product, never supported during the current century, is that it thinks FTEs cost less than using any indexes that may (or may not) exist. You've not established in your email that there are any indexes or posted DDL or provided much of anything else that would be helpful.
I would think moving from the Jurassic to 10.2.0.4, or above, would be your first priority.

Question on physical reads

Is RMAN I/Os accounted in physical reads stat?
I mean, do the blocks read from disk by RMAN to backup the database get accounted in physical reads statistic?
One of our databases has a value for physical read total IO requests higher than physical reads so I guess the physical reads missing are RMAN's.
Thanks in advance

Statistics have not the same unit so you cannot compare them directly:
>
physical read total IO requests
Number of read requests which read one or more database blocks for all instance activity including application, backup and recovery, and other utilities. The difference between this value and "physical read total multi block requests" gives the total number of single block read requests.
>
and
>
physical reads
Total number of data blocks read from disk. This value can be greater than the value of "physical reads direct" plus "physical reads cache" as reads into process private buffers also included in this statistic.
>
You should compare physical read total IO requests with:
>
physical read IO requests
Number of read requests for application activity (mainly buffer cache and direct load operation) which read one or more database blocks per request. This is a subset of "physical read total IO requests" statistic.
>
Edited by: P. Forstmann on 9 avr. 2013 12:57

Physical reads

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