More used index
Hi,
I`m doing a performance about some access and i have a table with a lot of indexes (more than 20) i activate the monitoring of the index and i find that all of index are using in some moment but how can i identify if these indexes are using only one time in the night for a specific select or is using all time for a lot of select???. Is possible to find the more used indexes in the different explain plan??.
The database is 10.2.0.3
Best Regard.
I had the same requirement once, to find out the count of indexes used for particular tablespace for given snapshot(with help of some links prepared the below)
If you have license to AWR views, you can try below
Here is the sql:
col object_name for a30
col tablespace_anme fora 12
col count for 9999
col operation for a35
col options for a25
set lines 160
select c.*, d.tablespace_name
from (select
a.object_name ,
a.operation ,
a.options ,
count(1)
from
dba_hist_sql_plan a,
dba_hist_sqlstat b
where
a.object_owner ='&a'
and
a.operation like '%INDEX%'
and
a.sql_id = b.sql_id
and b.snap_id between &a and &b
group by
a.object_name,
a.operation,
a.options
order by
4 desc) c,
dba_segments d
where c.object_name=d.segment_name
and d.tablespace_name='&a'
Edited by: vreddy on Aug 29, 2012 9:04 AM
Edited by: vreddy on Aug 29, 2012 9:07 AM
Similar Messages
-
How to make sql to use index/make to query to perform better
Hi,
I have 2 sql query which results the same.
But both has difference in SQL trace.
create table test_table
(u_id number(10),
u_no number(4),
s_id number(10),
s_no number(4),
o_id number(10),
o_no number(4),
constraint pk_test primary key(u_id, u_no));
insert into test_table(u_id, u_no, s_id, s_no, o_id, o_no)
values (2007030301, 1, 1001, 1, 2001, 1);
insert into test_table(u_id, u_no, s_id, s_no, o_id, o_no)
values (2007030302, 1, 1001, 1, 2001, 2);
insert into test_table(u_id, u_no, s_id, s_no, o_id, o_no)
values (2007030303, 1, 1001, 1, 2001, 3);
insert into test_table(u_id, u_no, s_id, s_no, o_id, o_no)
values (2007030304, 1, 1001, 1, 2001, 4);
insert into test_table(u_id, u_no, s_id, s_no, o_id, o_no)
values (2007030305, 1, 1002, 1, 1001, 2);
insert into test_table(u_id, u_no, s_id, s_no, o_id, o_no)
values (2007030306, 1, 1002, 1, 1002, 1);
commit;
CREATE INDEX idx_test_s_id ON test_table(s_id, s_no);
set autotrace on
select s_id, s_no, o_id, o_no
from test_table
where s_id <> o_id
and s_no <> o_no
union all
select o_id, o_no, s_id, s_no
from test_table
where s_id <> o_id
and s_no <> o_no;
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=6 Card=8 Bytes=416)
1 0 UNION-ALL
2 1 TABLE ACCESS (FULL) OF 'TEST_TABLE' (TABLE) (Cost=3 Card=4 Bytes=208)
3 1 TABLE ACCESS (FULL) OF 'TEST_TABLE' (TABLE) (Cost=3 Card=4 Bytes=208)
Statistics
223 recursive calls
2 db block gets
84 consistent gets
0 physical reads
0 redo size
701 bytes sent via SQL*Net to client
508 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
5 sorts (memory)
0 sorts (disk)
8 rows processed
-- i didnt understand why the above query is not using the index idx_test_s_id.
-- But still it is faster
select s_id, s_no, o_id, o_no
from test_table
where (u_id, u_no) in
(select u_id, u_no from test_table
minus
select u_id, u_no from test_table
where s_id = o_id
or s_no = o_no)
union all
select o_id, o_no, s_id, s_no
from test_table
where (u_id, u_no) in
(select u_id, u_no from test_table
minus
select u_id, u_no from test_table
where s_id = o_id
or s_no = o_no);
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=16 Card=2 Bytes=156)
1 0 UNION-ALL
2 1 FILTER
3 2 TABLE ACCESS (FULL) OF 'TEST_TABLE' (TABLE) (Cost=3 Card=6 Bytes=468)
4 2 MINUS
5 4 INDEX (UNIQUE SCAN) OF 'PK_TEST' (INDEX (UNIQUE)) (Cost=1 Card=1 Bytes=26)
6 4 TABLE ACCESS (BY INDEX ROWID) OF 'TEST_TABLE' (TABLE) (Cost=2 Card=1 Bytes=78)
7 6 INDEX (UNIQUE SCAN) OF 'PK_TEST' (INDEX (UNIQUE)) (Cost=1 Card=1)
8 1 FILTER
9 8 TABLE ACCESS (FULL) OF 'TEST_TABLE' (TABLE) (Cost=3 Card=6 Bytes=468)
10 8 MINUS
11 10 INDEX (UNIQUE SCAN) OF 'PK_TEST' (INDEX (UNIQUE)) (Cost=1 Card=1 Bytes=26)
12 10 TABLE ACCESS (BY INDEX ROWID) OF 'TEST_TABLE' (TABLE) (Cost=2 Card=1 Bytes=78)
13 12 INDEX (UNIQUE SCAN) OF 'PK_TEST' (INDEX (UNIQUE)) (Cost=1 Card=1)
Statistics
53 recursive calls
8 db block gets
187 consistent gets
0 physical reads
0 redo size
701 bytes sent via SQL*Net to client
508 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
4 sorts (memory)
0 sorts (disk)
8 rows processed
-- The above query is using index PK_TEST. But still it has FULL SCAN to the
-- table two times it has the more cost.
1st query --> SELECT STATEMENT Optimizer=ALL_ROWS (Cost=6 Card=8 Bytes=416)
2nd query --> SELECT STATEMENT Optimizer=ALL_ROWS (Cost=16 Card=2 Bytes=156)
My queries are:
1) performance wise which query is better?
2) how do i make the 1st query to use an index
3) is there any other method to get the same result by using any index
Appreciate your immediate help.
Best regards
MuthuHi William
Nice...it works.. I have added "o_id" and "o_no" are in part of the index
and now the query uses the index
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=2 Card=8 Bytes=416)
1 0 UNION-ALL
2 1 INDEX (FULL SCAN) OF 'IDX_TEST_S_ID' (INDEX) (Cost=1 Card=4 Bytes=208)
3 1 INDEX (FULL SCAN) OF 'IDX_TEST_S_ID' (INDEX) (Cost=1 Card=4 Bytes=208)
Statistics
7 recursive calls
0 db block gets
21 consistent gets
0 physical reads
0 redo size
701 bytes sent via SQL*Net to client
507 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
8 rows processed
But my questions are:
1) In a where clause, if "<>" condition is used, then, whether the system will use the index. Because I have observed in several situations even though the column in where clause is indexed, since the where condition is "like" or "is null/is not null"
then the index is not used. Same as like this, i assumed, if we use <> then indexes will not be used. Is it true?
2) Now, after adding "o_id" and "o_no" columns to the index, the Execution plan is:
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=2 Card=8 Bytes=416)
1 0 UNION-ALL
2 1 INDEX (FULL SCAN) OF 'IDX_TEST_S_ID' (INDEX) (Cost=1 Card=4 Bytes=208)
3 1 INDEX (FULL SCAN) OF 'IDX_TEST_S_ID' (INDEX) (Cost=1 Card=4 Bytes=208)
Before it was :
Execution Plan
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=6 Card=8 Bytes=416)
1 0 UNION-ALL
2 1 TABLE ACCESS (FULL) OF 'TEST_TABLE' (TABLE) (Cost=3 Card=4 Bytes=208)
3 1 TABLE ACCESS (FULL) OF 'TEST_TABLE' (TABLE) (Cost=3 Card=4 Bytes=208)
Difference only in Cost (reduced), not in Card, Bytes.
Can you explain, how can i decide which makes the performace better (Cost / Card / Bytes). Full Scan / Range Scan?
On statistics also:
Before:
Statistics
52 recursive calls
0 db block gets
43 consistent gets
0 physical reads
0 redo size
701 bytes sent via SQL*Net to client
507 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
8 rows processed
After:
Statistics
7 recursive calls
0 db block gets
21 consistent gets
0 physical reads
0 redo size
701 bytes sent via SQL*Net to client
507 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
8 rows processed
Difference in recursive calls & consistent gets.
Which one shows the query with better performance?
Please explain..
Regards
Muthu -
Using Index Vs dbms_stats.gather_table_stats
Hello All,
I would like to know in what situation would we benefit from using index and not analyse table as it takes time and in what situation analysing table is more beneficial then indexes.
I have a task which creates 14 tables CATS, 2nd table is depended on 1st table for eg create table as t2 as select * from t1 so on and so forth. I am indexing all the 14 tables and gathering statistics.. my colleague says that if tables are indexed then gathering statistics is not required. So table1 - table14 need not have gather statistics. This module is used for large volume of data extract.
My task is like
1. create table t1 as select * from <table_name>
create index
gather_table_stats
2. create table t2 as select * from t1
create index
gather_table_stats
3. create table t3 as select * from t2
create index
gather_table_stats
Regards,
RashidaRashida wrote:
Hello All,
I would like to know in what situation would we benefit from using index and not analyse table as it takes time and in what situation analysing table is more beneficial then indexes. You are comparing Apples and Oranges. They are different. They cant be compared.
ANALYSE is done on a table to collect statistics of the table. CBO needs this information to get the best execution plan. INDEX is a data structure like your table. They help you in searching your data in your table in a faster way.
For the optimizer to use your INDEX you need to have statistics of your TABLE and INDEX collected.
I have a task which creates 14 tables CATS, 2nd table is depended on 1st table for eg create table as t2 as select * from t1 so on and so forth. I am indexing all the 14 tables and gathering statistics.. my colleague says that if tables are indexed then gathering statistics is not required. That is a totally wrong statement. This only means your colleague does not know about both INDEX and Statistics. And also how CBO works. -
How can i use index in select query.. facing problem with the select query.
Hi Friends,
I am facing a serious problem in one of the select query. It is taking a lot of time to fetch data in Production Scenario.
Here is the query:
SELECT * APPENDING CORRESPONDING FIELDS OF TABLE tbl_summary
FROM ztftelat LEFT JOIN ztfzberep
ON ztfzberep~gjahr = st_input-gjahr
AND ztfzberep~poper = st_input-poper
AND ztfzberepcntr = ztftelatrprctr
WHERE rldnr = c_telstra_accounting
AND rrcty = c_actual
AND rvers = c_ver_001
AND rbukrs = st_input-bukrs
AND racct = st_input-saknr
AND ryear = st_input-gjahr
And rzzlstar in r_lstar
AND rpmax = c_max_period.
There are 5 indices present for Table ZTFTELAT.
Indices of ZTFTELAT:
Name Description
0 Primary key( RCLNT,RLDNR,RRCTY,RVERS,RYEAR,ROBJNR,SOBJNR,RTCUR,RUNIT,DRCRK,RPMAX)
005 Profit (RCLNT,RPRCTR)
1 Ledger, company code, account (RLDNR,RBUKRS, RACCT)
2 Ledger, company code, cost center (RLDNR, RBUKRS,RCNTR)
3 Account, cost center (RACCT,RCNTR)
4 RCLNT/RLDNR/RRCTY/RVERS/RYEAR/RZZAUFNR
Z01 Activity Type, Account (RZZLSTAR,RACCT)
Z02 RYEAR-RBUKRS- RZZZBER-RLDNR
Can anyone help me out why it is taking so much time and how we can reduce it ? and also tell me if I want to use index number 1 then how can I use?
Thanks in advance.Hi Shiva,
I am using two more select queries with the same manner ....
here are the other two select query :
***************1************************
SELECT * APPENDING CORRESPONDING FIELDS OF TABLE tbl_summary
FROM ztftelpt LEFT JOIN ztfzberep
ON ztfzberep~gjahr = st_input-gjahr
AND ztfzberep~poper = st_input-poper
AND ztfzberepcntr = ztftelptrprctr
WHERE rldnr = c_telstra_projects
AND rrcty = c_actual
AND rvers = c_ver_001
AND rbukrs = st_input-bukrs
AND racct = st_input-saknr
AND ryear = st_input-gjahr
and rzzlstar in r_lstar
AND rpmax = c_max_period.
and the second one is
*************************2************************
SELECT * APPENDING CORRESPONDING FIELDS OF TABLE tbl_summary
FROM ztftelnt LEFT JOIN ztfzberep
ON ztfzberep~gjahr = st_input-gjahr
AND ztfzberep~poper = st_input-poper
AND ztfzberepcntr = ztftelntrprctr
WHERE rldnr = c_telstra_networks
AND rrcty = c_actual
AND rvers = c_ver_001
AND rbukrs = st_input-bukrs
AND racct = st_input-saknr
AND ryear = st_input-gjahr
and rzzlstar in r_lstar
AND rpmax = c_max_period.
for both the above table program is taking very less time .... although both the table used in above queries have similar amount of data. And i can not remove the APPENDING CORRESPONDING. because i have to append the data after fetching from the tables. if i will not use it will delete all the data fetched earlier.
Thanks on advanced......
Sourabh -
Feature Request UI builder: More use of Ctrl + ... similar to LabVIEW
Would like to see more use of the Control + Key for common features that are in LabVIEW. Run for example is Ctrl + R
I agree this option would be great to have built in automatically. It might also be nice to allow auto-indixing of 2d (or more) arrays going into for loops where it will iterate through all dimensions an grab the (i,j) single elements and add an i and j index inside the loop, instead of nesting loops inside of each other. I guess these features cater to the power users who want to save any amount of coding possible.
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA -
Best way of Using Index on a Table.
I am trying to understand the phenomena of using INDEX on a Table
need some guidance!!!
Let us take this scenario
I have a table "MYRECORD" which has 4 attributes(or coulombs)
1. "STATE" (varchar) // this can have 49 different values like newyork, dehli etc
2. "YEAR" //a year like 2007
3. "MONTH" //a month like JAN,FEB etc
4. "CAT" (int) // type(category) of data represented by values 0 to 40
with a PRIMARY KEY(STATE,YEAR,MONTH,CAT)
now i will create index
1. INX_myrecord (STATE,YEAR,MONTH) on table MYRECORD
so now my question is
1. what is the effect on performance of DB it makes?
2. when I use a query
SELECT * FROM MYRECORD WHERE STATE="dehli" AND YEAR=2007 AND MONTH="JAN";
how will it get processed if index is created and not created.
3. how can I refer a index by name in a query if so possible?
Cheers,
UD
Message was edited by:
UDAYYou have edited your post. Now you have a primary key consisting of state, year, month and cat which makes an index on state, year and month useless as the already existing primary key can provide for retrieval of rows by index. If you don't have other columns - or just few other not being large varchar2 columns - you should have created the table as an IOT (Index Organized Table - avoiding to have separate table and index containing - nearly - the same data) in the first place.
As a primary key by definition can contain only unique non null values, a query like SELECT * FROM MYRECORD WHERE STATE='dehli' AND YEAR=2007 AND MONTH='JAN' cannot give you more than the number of distinct cat values (0 .. 40) + 1 (if cat can be null - presumed one/some of the corresponding state, year and month is not null)
The information processing depends principally of the query, the mere presence of an index does not make sure it will be used. If an index is used it means the index will be searched first then the table rows will be accessed by rowids contained in the index (usually a single row or a range of rows - a rather small number of them - is retrieved this way, your select for example). Submitting something like SELECT * FROM MYRECORD WHERE YEAR=2007 AND cat=33 would most likely produce a full table scan of myrecord table ignoring the primary key.
Regards
Etbin -
Not Using Index on File Server When Accessing User Files Directly on Server
It appears to me that on a server with an indexed network share (Desktop Experience and Search Indexing roles/features installed), if you access the share directly on the server using its drive path, you can search the folders using the index, which
is much faster and supports finding words inside of the files in seconds). However, if you access the same shared folder via its network path from the server itself, the server ignores the index. I have this experience/problem across all shared folders on
the Windows 2012 R2 Server. Details and my most specific goal follows.
In addition to a laptop, I frequently work directly on a Windows Server 2012 R2 computer. We have Redirected Folders set up on DFS (for failover redundancy) so that my Documents folder is in:
\\network\redirections\user\documents. This all works fine on Windows 7 and 8 client computers connected to the network via Offline Files.
The problem is on the server itself. The server has Desktop Experience enabled and Windows Search is installed. If I navigate manually through the DFS root folder to my documents folder, I can search and it properly uses the index. This proves the location
is properly indexed. However, if I access the folders through the official "Documents" folder from the Folder Redirection (a network share pointing to the same server computer I'm working on), it performs an un-indexed search (slow and ignores file
contents, but does find files eventually if the search term is in their filename). Is there a way to force the server to use the indexed search on the Redirected Folders (my Documents folder in particular) when working on that server when logged in locally
on that server?
I suspect a workaround would be to go into the Registry and manually change the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders to point to the local DFS folder instead of the network share name, but at least one problem
with this is then if I save files with links to other files (e.g., a linked Excel table in a PowerPoint, a mail merge to Access database in Word, etc.) on the server computer, those links will point to d:\DFSroot\... (a physical drive on the computer) instead
of \\network\redirections\user\... (a universally accessible network path) and so none of the other computers will be able to find the linked files, defeating one of the
major benefits of using Redirected Folders.
I can't believe that I need to choose between indexed searching and proper path names in saved files. Surely there is a way to use an indexed search on the server itself?
If you need any more info to help me troubleshoot, please let me know.
Thanks for any help,
ColinHi Colin,
It seems that we can not use indexed search on DFS shares. Windows Search works well when users directly access the server. That is, the server is not made available through Distributed File System (DFS).
For more detailed information, you could refer to the links below:
Windows Search Service, Clustered File Services, DFS, Win7 Libraries
https://social.technet.microsoft.com/Forums/windowsserver/en-US/31ac4c16-948b-4ca4-b18f-3a339cdfd5b9/windows-search-service-clustered-file-services-dfs-win7-libraries?forum=winserverfiles
Windows Browse and Organize Features
https://technet.microsoft.com/en-us/library/dd744693(WS.10).aspx
Best Regards,
Mandy
Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact [email protected] -
select *
from hrm_career x
WHERE x.begin_date = ( SELECT MAX(begin_date)
FROM hrm_career y
WHERE y.employee_id = x.employee_id AND
begin_date <= SYSDATE AND
primary_job = 'Y') AND
x.primary_job = 'Y'
I have the above query which is not using the index created on the BEGIN_DT column
I tried to force using still not using
but when i apply a value say
select *
from hrm_career x
WHERE x.begin_date ='10-20-2007'
It is using index and resulting in very fast response
Can some throw some ideas on it...
Where should i look into here ..SQL> set autotrace traceonly
SQL> select *
2 from hrm_career x
3 WHERE x.begin_date = ( SELECT MAX(begin_date)
4 FROM hrm_career y
5 WHERE y.employee_id = x.employee_id AND
6 begin_date <= SYSDATE AND
7 primary_job = 'Y') AND
8 x.primary_job = 'Y';
13454 rows selected.
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1417 Card=152 Bytes=
35568)
1 0 FILTER
2 1 SORT (GROUP BY) (Cost=1417 Card=152 Bytes=35568)
3 2 HASH JOIN (Cost=254 Card=47127 Bytes=11027718)
4 3 INDEX (FAST FULL SCAN) OF 'HRM_CAREER_PK' (UNIQUE) (
Cost=12 Card=25026 Bytes=500520)
5 3 TABLE ACCESS (FULL) OF 'HRM_CAREER' (Cost=81 Card=25
335 Bytes=5421690)
Statistics
3671 recursive calls
9 db block gets
1758 consistent gets
2130 physical reads
0 redo size
2217762 bytes sent via SQL*Net to client
10359 bytes received via SQL*Net from client
898 SQL*Net roundtrips to/from client
128 sorts (memory)
1 sorts (disk)
13454 rows processed
TKPROF
TKPROF: Release 9.2.0.6.0 - Production on Wed Dec 12 18:40:56 2007
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Trace file: qnhg_ora_500.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: CHOOSE
Parsing user id: 30 (ADMIN)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 1 0.00 0.00
SQL*Net message from client 1 34.45 34.45
select condition
from
cdef$ where rowid=:1
call count cpu elapsed disk query current rows
Parse 4 0.00 0.00 0 0 0 0
Execute 4 0.00 0.00 0 0 0 0
Fetch 4 0.00 0.00 0 8 0 4
total 12 0.00 0.00 0 8 0 4
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: SYS (recursive depth: 1)
Rows Row Source Operation
1 TABLE ACCESS BY USER ROWID CDEF$
select *
from hrm_career x
WHERE x.begin_date = ( SELECT MAX(begin_date)
FROM hrm_career y
WHERE y.employee_id = x.employee_id AND
begin_date <= SYSDATE AND
primary_job = 'Y') AND
x.primary_job = 'Y'
call count cpu elapsed disk query current rows
Parse 1 0.00 0.07 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 898 0.00 2.39 2038 946 9 13454
total 900 0.00 2.46 2038 946 9 13454
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN)
Rows Row Source Operation
13454 FILTER
25335 SORT GROUP BY
67496 HASH JOIN
25333 INDEX FAST FULL SCAN HRM_CAREER_PK (object id 25292)
25336 TABLE ACCESS FULL HRM_CAREER
Rows Execution Plan
0 SELECT STATEMENT GOAL: CHOOSE
13454 FILTER
25335 SORT (GROUP BY)
67496 HASH JOIN
25333 INDEX GOAL: ANALYZED (FAST FULL SCAN) OF 'HRM_CAREER_PK'
(UNIQUE)
25336 TABLE ACCESS GOAL: ANALYZED (FULL) OF 'HRM_CAREER'
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 898 0.00 0.00
SQL*Net more data to client 877 0.00 0.05
db file sequential read 1 0.01 0.01
db file scattered read 60 0.00 0.14
direct path write 9 0.00 0.00
direct path read 125 0.05 0.13
SQL*Net message from client 898 0.02 1.47
DELETE FROM PLAN_TABLE
WHERE
STATEMENT_ID=:1
call count cpu elapsed disk query current rows
Parse 2 0.00 0.00 0 0 0 0
Execute 2 0.00 0.00 0 6 6 6
Fetch 0 0.00 0.00 0 0 0 0
total 4 0.00 0.00 0 6 6 6
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN)
Rows Row Source Operation
0 DELETE
0 TABLE ACCESS FULL PLAN_TABLE
Rows Execution Plan
0 DELETE STATEMENT GOAL: CHOOSE
0 DELETE OF 'PLAN_TABLE'
0 TABLE ACCESS (FULL) OF 'PLAN_TABLE'
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 2 0.00 0.00
SQL*Net message from client 2 14.77 14.79
select o.owner#,o.name,o.namespace,o.remoteowner,o.linkname,o.subname,
o.dataobj#,o.flags
from
obj$ o where o.obj#=: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 0 0 0 0
Fetch 1 0.00 0.00 0 3 0 1
total 3 0.00 0.00 0 3 0 1
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: SYS (recursive depth: 1)
EXPLAIN PLAN SET STATEMENT_ID='PLUS74964' FOR select *
from hrm_career x
WHERE x.begin_date = ( SELECT MAX(begin_date)
FROM hrm_career y
WHERE y.employee_id = x.employee_id AND
begin_date <= SYSDATE AND
primary_job = 'Y') AND
x.primary_job = 'Y'
call count cpu elapsed disk query current rows
Parse 1 0.00 0.01 0 4 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 0 0.00 0.00 0 0 0 0
total 2 0.00 0.01 0 4 0 0
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN)
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 1 0.00 0.00
SQL*Net message from client 1 0.00 0.00
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, cpu_cost, io_cost, temp_space, access_predicates,
filter_predicates )
values
(:1,SYSDATE,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,:15,:16,:17,:18,:19,
:20,:21,:22,:23,:24,:25,:26,:27)
call count cpu elapsed disk query current rows
Parse 1 0.00 0.00 0 0 0 0
Execute 6 0.00 0.00 0 3 6 6
Fetch 0 0.00 0.00 0 0 0 0
total 7 0.00 0.00 0 3 6 6
Misses in library cache during parse: 1
Misses in library cache during execute: 2
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN) (recursive depth: 1)
Rows Execution Plan
0 INSERT STATEMENT GOAL: CHOOSE
select o.name, u.name
from
sys.obj$ o, sys.user$ u where obj# = :1 and owner# = user#
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
Parsing user id: SYS (recursive depth: 1)
SELECT ID ID_PLUS_EXP,PARENT_ID PARENT_ID_PLUS_EXP,LPAD(' ',2*(LEVEL-1))
||OPERATION||DECODE(OTHER_TAG,NULL,'','*')||DECODE(OPTIONS,NULL,'','
('||OPTIONS||')')||DECODE(OBJECT_NAME,NULL,'',' OF '''||OBJECT_NAME||'''')
||DECODE(OBJECT_TYPE,NULL,'',' ('||OBJECT_TYPE||')')||DECODE(ID,0,
DECODE(OPTIMIZER,NULL,'',' Optimizer='||OPTIMIZER))||DECODE(COST,NULL,'','
(Cost='||COST||DECODE(CARDINALITY,NULL,'',' Card='||CARDINALITY)
||DECODE(BYTES,NULL,'',' Bytes='||BYTES)||')') PLAN_PLUS_EXP,OBJECT_NODE
OBJECT_NODE_PLUS_EXP
FROM
PLAN_TABLE START WITH ID=0 AND STATEMENT_ID=:1 CONNECT BY PRIOR ID=PARENT_ID
AND STATEMENT_ID=:1 ORDER BY ID,POSITION
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 2 0.00 0.00 0 22 0 6
total 4 0.00 0.00 0 22 0 6
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN)
Rows Row Source Operation
6 SORT ORDER BY
6 CONNECT BY WITH FILTERING
1 NESTED LOOPS
1 TABLE ACCESS FULL PLAN_TABLE
1 TABLE ACCESS BY USER ROWID PLAN_TABLE
5 NESTED LOOPS
6 BUFFER SORT
6 CONNECT BY PUMP
5 TABLE ACCESS FULL PLAN_TABLE
Rows Execution Plan
0 SELECT STATEMENT GOAL: CHOOSE
6 SORT (ORDER BY)
6 CONNECT BY (WITH FILTERING)
1 NESTED LOOPS
1 TABLE ACCESS (FULL) OF 'PLAN_TABLE'
1 TABLE ACCESS (BY USER ROWID) OF 'PLAN_TABLE'
5 NESTED LOOPS
6 BUFFER (SORT)
6 CONNECT BY PUMP
5 TABLE ACCESS (FULL) OF 'PLAN_TABLE'
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 2 0.00 0.00
SQL*Net message from client 2 0.09 0.09
SELECT ID ID_PLUS_EXP,OTHER_TAG OTHER_TAG_PLUS_EXP,OTHER OTHER_PLUS_EXP
FROM
PLAN_TABLE WHERE STATEMENT_ID=:1 AND OTHER_TAG IS NOT NULL ORDER BY ID
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 3 0 0
total 3 0.00 0.00 0 3 0 0
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN)
Rows Row Source Operation
0 SORT ORDER BY
0 TABLE ACCESS FULL PLAN_TABLE
Rows Execution Plan
0 SELECT STATEMENT GOAL: CHOOSE
0 SORT (ORDER BY)
0 TABLE ACCESS (FULL) OF 'PLAN_TABLE'
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 2 0.00 0.00
SQL*Net message from client 2 0.00 0.00
ALTER SESSION SET EVENTS '10046 trace name context off'
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 0 0.00 0.00 0 0 0 0
total 2 0.00 0.00 0 0 0 0
Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: 30 (ADMIN)
OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS
call count cpu elapsed disk query current rows
Parse 7 0.00 0.09 0 4 0 0
Execute 8 0.00 0.00 0 6 6 6
Fetch 901 0.00 2.39 2038 971 9 13460
total 916 0.00 2.49 2038 981 15 13466
Misses in library cache during parse: 6
Misses in library cache during execute: 1
Elapsed times include waiting on following events:
Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 906 0.00 0.00
SQL*Net message from client 906 34.45 50.82
SQL*Net more data to client 877 0.00 0.05
db file sequential read 1 0.01 0.01
db file scattered read 60 0.00 0.14
direct path write 9 0.00 0.00
direct path read 125 0.05 0.13
OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS
call count cpu elapsed disk query current rows
Parse 7 0.00 0.00 0 0 0 0
Execute 11 0.00 0.00 0 3 6 6
Fetch 5 0.00 0.00 0 11 0 5
total 23 0.00 0.00 0 14 6 11
Misses in library cache during parse: 4
Misses in library cache during execute: 2
9 user SQL statements in session.
6 internal SQL statements in session.
15 SQL statements in session.
5 statements EXPLAINed in this session.
Trace file: qnhg_ora_500.trc
Trace file compatibility: 9.02.00
Sort options: default
3 sessions in tracefile.
12 user SQL statements in trace file.
8 internal SQL statements in trace file.
15 SQL statements in trace file.
11 unique SQL statements in trace file.
5 SQL statements EXPLAINed using schema:
ADMIN.prof$plan_table
Default table was used.
Table was created.
Table was dropped.
3945 lines in trace file.
Message was edited by:
Maran Viswarayar -
How is it possible to use Index Seek for LIKE %search-string% case?
Hello,
I have the following SP:
CREATE PROCEDURE dbo.USP_SAMPLE_PROCEDURE(@Beginning nvarchar(15))
AS
SELECT * FROM HumanResources.Employee
WHERE NationalIDNumber LIKE @Beginning + N'%';
GO
If I run the sp first time with param: N'94', then the following plan is generated and added to the cache:
SQL Server "sniffs" the input value (94) when compiling the query. So for this param using Index Seek for AK_Employee_NationalIDNumber index will be the best option. On the other hand, the query plan should be generic enough to be able to handle
any values specified in the @Beginning param.
If I call the sp with @Beginning =N'%94':
EXEC dbo.USP_SAMPLE_PROCEDURE N'%94'
I see the same execution plan as above. The question is how is it possible to reuse this execution plan in this case? To be more precise, how
Index Seek can be used in case LIKE %search-string% case. I expected that
ONLY Index Scan operation can be used here.
AlexeyThe key is that the index seek operator includes both seek (greater than and less than) and a predicate (LIKE). With the leading wildcard, the seek is effectively returning all rows just like a scan and the filter returns only rows matching
the LIKE expression.
Do you want to say that in case of leading wildcard, expressions Expr1007 and Expr1008 (see image below) calculated such a way that
Seek Predicates retrieve all rows from the index. And only
Predicate does the real job by taking only rows matching the Like expression? If this is the case, then it explains how
Index Seek can be used to resolve such queries: LIKE N'%94'.
However, it leads me to another question: Since
Index Seek in
this particular case scans
all the rows, what is the difference between
Index Seek and Index Scan?
According to
MSDN:
The Index Seek operator uses the seeking ability of indexes to retrieve rows from a nonclustered index.
The storage engine uses the index to process
only those rows that satisfy the SEEK:() predicate. It optionally may include a WHERE:() predicate, which the storage engine will evaluate against all rows that satisfy the SEEK:() predicate (it does not use the indexes to do this).
The Index Scan operator retrieves
all rows from the nonclustered index specified in the Argument column. If an optional WHERE:() predicate appears in the Argument column, only those rows that satisfy the predicate are returned.
It seems like Index Scan is a special case of Index Seek,
which means that when we see Index Seek in the execution plan, it does NOT mean that storage engine does NOT scan all rows. Right?
Alexey -
CBO calculates un acceptable cost while using index.
Hi,
I was wondering to see the execution plan for both the case using index/without index.
We are using oracle 10G(10.2.0.3.0) with RAC in production at O/S:- sun solaris 10.
Java based application is running in this database. One of the sql query is taking long time to fetch the records. I analyzed the sql plan and noticed the FTS. I created indexes to the column(s) which is refering in where clauses. I noticed a strage behavior. Execution plan shows that the CBO is using right path but its not acceptable as application is time outs while return the rows.
first execution plan with/without index (not using the index).
PLAN_TABLE_OUTPUT
Plan hash value: 419342726
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 196 | 3332 | 67845 (3)| 00:13:35 |
|* 1 | TABLE ACCESS FULL | CWDBENUMDESCRIPTIONS | 1 | 35 | 3 (0)| 00:00:01 |
| 2 | SORT GROUP BY | | 196 | 3332 | 67845 (3)| 00:13:35 |
|* 3 | TABLE ACCESS FULL| CWORDERINSTANCE | 51466 | 854K| 67837 (3)| 00:13:35 |
Predicate Information (identified by operation id):
1 - filter("ERR"."CODE"=:B1)
3 - filter("OI"."ERROR_CODE" IS NOT NULL AND "OI"."DIVISION"='OR9' AND
"OI"."ACTIVE"=TO_NUMBER(:1) AND "OI"."ORDER_STATE"<>'O_NR_NS' AND
"OI"."ORDER_STATE"<>'C_C_QR' AND "OI"."ORDER_STATE"<>'O_NR_NS_D')
SQl query was modified to force the index to use /*+ index(oi oi_div) */ the execution is as below:-
PLAN_TABLE_OUTPUT
Plan hash value: 1157277132
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 196 | 3332 | 394K (1)| 01:18:52 |
|* 1 | TABLE ACCESS FULL | CWDBENUMDESCRIPTIONS | 1 | 35 | 3 (0)| 00:00:01 |
| 2 | SORT GROUP BY | | 196 | 3332 | 394K (1)| 01:18:52 |
|* 3 | TABLE ACCESS BY INDEX ROWID| CWORDERINSTANCE | 51466 | 854K| 394K (1)| 01:18:52 |
|* 4 | INDEX RANGE SCAN | OI_DIV | 3025K| | 14226 (1)| 00:02:51 |
Predicate Information (identified by operation id):
1 - filter("ERR"."CODE"=:B1)
3 - filter("OI"."ERROR_CODE" IS NOT NULL AND "OI"."ACTIVE"=TO_NUMBER(:1) AND
"OI"."ORDER_STATE"<>'O_NR_NS' AND "OI"."ORDER_STATE"<>'C_C_QR' AND
"OI"."ORDER_STATE"<>'O_NR_NS_D')
My questions are here:-
1). why FTS is less costly comparing index scan where there are 15000000 rows in the table.
2). while forcing index to use cost increase drastically (the statistics is latest one analyzed on 6th of feb 2009)
3). what should i suppose to change to get the performance benefit.
Thanks,
Pradeepuser587112 wrote:
select null, oi.division, oi.METADATATYPE, oi.ERROR_CODE,
( select err.DESCRIPTION
FROM CWDBENUMDESCRIPTIONS err
WHERE oi.ERROR_CODE = err.CODE
count(*)
from CWORDERINSTANCE oi
where
oi.ERROR_CODE is not null
and oi.division in ('BK9')
and oi.order_state not in ('O_NR_NS_D', 'C_C_QR', 'O_NR_NS')
and oi.metadatatype = :1
and oi.duedate>=:2
and oi.active = :3
group by oi.division, oi.metadatatype, oi.error_code
order by oi.division, oi.metadatatype, oi.error_code
In this query, if we use as it is how its being displayed, it runs like a rocket, but if we change division in ('OR9') instead of 'BK9' it does not use index and leads to time out the application.
Number of records division
1964690 ---------------- why this field is null ?
3090666 OR9
3468 BA9
1242 EL9
2702 IN9
258 EU9
196198 DT9
1268 PA9
8 BK9
2332 BH9
1405009 TP9
According to the stats in your original execution plan, it looks like you have a histogram on this column, and the index you want to use is on just the division column.
Oracle estimate for 'OR9' is 3M rowids from the index, resulting in 50,000+ rows from the table - that's a lot of work - it's not surprising that the optimizer chose a tablescan for 'OR9' - but chose to use the index for 'BK9' which has only 8 rows.
How often do you want to run this query ? And how accurate does the answer have to be ?
If you want this query to run faster even when it's processing a huge number of rows, one option would be to create a materialized view over the data that could supply the result set much more efficiently (possibly getting your front-end code to call a materialized view refresh before running the query).
The only other altenative is probably to create an index that covers all the columns in the query so that you don't have to visit the table - and if you order them correctly you won't have to do a sort group by. I think this index should do the trick: (division, metadatatype, error_code,active, duedate,orderstate). You could also compress this index on at least the first column, but possibly on far more columns, to minimise the size,
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."
Stephen Hawking
To post code, statspack/AWR report, execution plans or trace files, start and end the section with the tag {noformat}{noformat} (lowercase, curly brackets, no spaces) so that the text appears in fixed format. -
USING INDEXES DEFINED ON TABLES IN SELECT STATEMENTS
Hi there,
I would like to ask a simple question, how i can use indexes defined on certain columns on one of my database tables in a select clause:
table name: B2TECDOC
schema name: AWDBT1M4
indexes defined: AWDBT1M4.B2TECDOC_B2TECDOCKEY
index AWDBT1M4.B2TECDOC_B2TECDOCKEY is defined on columns:
documentname
documenttype
organizationid
organizationtype
revision
sequence
versionnumbercould you help me construct a select sql using this index?
another question is will using this index in my select clause increase the overall query performance?
thanks
rohanA query like
SELECT *
FROM AWDBT1M4.B2TECDOC
WHERE documentname = <<some value>>
AND documenttype = <<some value>
AND organizationid = <<some value>>
AND organizationtype = <<some value>>
AND revision = <<some value>>
AND sequence = <<some value>>
AND versionnumber = <<some value>>should use the index.
An index is a more efficient way to access a relatively small fraction of the rows in the table. A table scan will be more efficient if you are trying to access a relatively large fraction of the rows in the table. Exactly what "small fraction" and "large fraction" means will depend on a variety of factors that the cost-based optimizer (CBO) attempts to evaluate in determing the query plan.
Justin -
Hi, I'm a fairly new user of Oracle XMLDB 9.2.0.4 so please bear with me. I registered a schema and inserted about 130k rows into an XMLType table. Retrieval time took a severe hit as expected, but I created some indexes and it seemed to solve the problem. Autotrace showed that indexes were working correctly.
However, delete does not seem to use those indexes, and instead performs a full table scan. The only difference between the statements used were:
SELECT * FROM <table> where existsNode(...)
DELETE FROM <table> where existsNode(...)
Does anyone know how to alleviate full table scans on deletes?
Thanks in advance,
JustinThanks for your time Mark.
I messed around with 9.2.0.4 a little more, and realized that delete will use the index if it's an element that is indexed (like your example pointed out). However, delete doesn't seem to use indexed attributes.
(Deleting based on an indexed element)
explain plan for
delete
from purchaseorder x
where existsNode ( value(x), '/PurchaseOrder/LineItems/LineItem[@ItemNumber="1"]/Part[@Id="715515011129"]') = 1
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | DELETE STATEMENT | | 1 | 19946 | 1 |
| 1 | DELETE | PURCHASEORDER | | | |
|* 2 | TABLE ACCESS BY INDEX ROWID| PURCHASEORDER | 1 | 19946 | 1 |
|* 3 | INDEX RANGE SCAN | IPURCHASEORDERUSER | 2 | | 1 |
(retrieving based on an indexed attribute)
explain plan for
select value(x)
from purchaseorder x
where existsNode ( value(x), '/PurchaseOrder/LineItems/LineItem[@ItemNumber="1"]/Part[@Id="715515011129"]') = 1
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 1 | 24142 | 6 |
|* 1 | INDEX RANGE SCAN | SYS_IOT_TOP_35381 | 1 | 2038 | 2 |
|* 2 | INDEX RANGE SCAN | SYS_IOT_TOP_35386 | 1 | 4214 | 2 |
| 3 | NESTED LOOPS | | 1 | 24142 | 6 |
| 4 | SORT UNIQUE | | | | |
|* 5 | INDEX UNIQUE SCAN | SYS_IOT_TOP_35386 | 1 | 4216 | 2 |
|* 6 | INDEX RANGE SCAN | ILINEITEMPARTNUMBER | 1 | | 2 |
|* 7 | TABLE ACCESS BY INDEX ROWID| PURCHASEORDER | 4 | 79704 | 1 |
|* 8 | INDEX UNIQUE SCAN | SYS_C003455 | 102 | | |
Predicate Information (identified by operation id):
1 - access("SYS_NT5e0stCgbSQ6Dg7Md7+/Y0A=="."NESTED_TABLE_ID"=:B1)
2 - access("SYS_NTyLtUmo5HRjCEB+0PWmS+kA=="."NESTED_TABLE_ID"=:B1)
5 - access("SYS_NTyLtUmo5HRjCEB+0PWmS+kA=="."ITEMNUMBER"=1)
filter("SYS_NTyLtUmo5HRjCEB+0PWmS+kA=="."SYS_NC00011$"='715515011129')
6 - access("SYS_NTyLtUmo5HRjCEB+0PWmS+kA=="."ITEMNUMBER"=1)
7 - filter(SYS_CHECKACL("SYS_ALIAS_4"."ACLOID","SYS_ALIAS_4"."OWNERID",xmltype(''<
privilege xmlns="http://xmlns.oracle.com/xdb/acl.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.oracle.com/xdb/acl.xsd
http://xmlns.oracle.com/xdb/acl.xsd DAV:http://xmlns.oracle.com/xdb/dav.xsd"><read-pr
operties/><read-contents/></privilege>''))=1)
8 - access("SYS_NTyLtUmo5HRjCEB+0PWmS+kA=="."NESTED_TABLE_ID"="SYS_ALIAS_4"."SYS_N
C0003400035$")
Note: cpu costing is off
(Deleting based on indexed attribute)
explain plan for
delete
from purchaseorder x
where existsNode ( value(x), '/PurchaseOrder/LineItems/LineItem[@ItemNumber="1"]/Part[@Id="715515011129"]') = 1
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | DELETE STATEMENT | | 1 | 19946 | 13 |
| 1 | DELETE | PURCHASEORDER | | | |
|* 2 | FILTER | | | | |
|* 3 | TABLE ACCESS FULL | PURCHASEORDER | 1 | 19946 | 2 |
|* 4 | COLLECTION ITERATOR PICKLER FETCH| | | | |
Predicate Information (identified by operation id):
2 - filter( EXISTS (SELECT /*+ */ 0 FROM
TABLE(SYS_OP_ATG(SYS_OP_ATG(:B1,10,11,3),2,3,3)) "KOKBF$" WHERE
SYS_OP_ATG(VALUE(KOKBF$),2,3,2)=1 AND SYS_OP_ATG(SYS_OP_ATG(VALUE(KOKBF$),4,5,3),2,3,2
)='715515011129'))
3 - filter(SYS_CHECKACL("SYS_ALIAS_4"."ACLOID","SYS_ALIAS_4"."OWNERID",xmltype(''<p
rivilege xmlns="http://xmlns.oracle.com/xdb/acl.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.oracle.com/xdb/acl.xsd
http://xmlns.oracle.com/xdb/acl.xsd DAV:http://xmlns.oracle.com/xdb/dav.xsd"><update/>
<unlink-from/></privilege>''))=1)
4 - filter(SYS_OP_ATG(VALUE(KOKBF$),2,3,2)=1 AND
SYS_OP_ATG(SYS_OP_ATG(VALUE(KOKBF$),4,5,3),2,3,2)='715515011129')
Note: cpu costing is off
Thanks again,
Justin -
I have a query which is taking 2 minutes to respond. When I see the explain plan, it said for two tables it is doing the full table scan. So I tried forcing to use the index on the inner tables(xcm, detail) of the views(vw_xcm , vw_vw_detail). But it is still not using indexes when the query is running. Please let me know if I am forcing the indexes right.
Here is my code
SELECT x.customer_gci AS hdr_borrower_gci,
x.industry_group_name AS hdr_borrower_sector,
x.industry_subgroup_name AS hdr_borrower_industry,
CAST (NULL AS number) AS hdr_incremental_fvo_amt,
x.industry_subgroup_code AS hdr_industry_cd,
x.industry_subgroup_name AS hdr_industry,
CAST (NULL AS integer) AS hdr_cds_tenor,
x.industry_group_code AS hdr_req_borrower_sector_cd,
x.industry_subgroup_code AS hdr_req_borrower_industry_cd,
x.customer_gci AS dtl_borrower_gci,
x.customer_name AS dtl_company_name,
(SELECT NVL (MAX (market_cap), 0)
FROM data_v2 kmv
WHERE kmv.asof_date = (SELECT MAX (actual_data_date)
FROM fvo_process_dtl dtl
WHERE dtl.process_name = 'KMV')
AND kmv.spineid = x.spineid
AND kmv.market_cap <> 0)
AS dtl_marketcap,
x.industry_subgroup_name AS dtl_industry,
x.dtl_region,
(SELECT SUM (NVL (notional, 0))
FROM vw_gcm
WHERE datestamp = (SELECT MAX (datestamp)
FROM vw_fvo_gcm_trade)
AND familygci = family_gci
AND rpt_product = 'LOAN'
AND rpt_risk_group = 'FVO')
AS dtl_current_fvo_amt,
NULL AS dtl_trader_liquidity_cd,
CAST (NULL AS number) AS dtl_manager_acceptable_amt,
NULL AS dtl_lastused_date,
NULL AS dtl_trader_comments,
NULL AS dtl_manager_comments,
CAST (NULL AS number) AS dtl_incremental_fvo_amt,
x.industry_subgroup_code AS dtl_industry_code,
x.spineid,
(SELECT SUBSTR (MAX(TO_CHAR (ratingdate, 'YYYYMMDD')
|| iss.issuerrating),
9
FROM issuerrating iss
WHERE iss.ratingschemeid =
(SELECT rs.ratingschemeid
FROM ratingscheme rs
WHERE rs.ratingschemename = 'SNP')
AND iss.ratingtypeid = (SELECT rt.ratingtypeid
FROM ratingtype rt
WHERE rt.ratingtypecode = 'LT')
AND iss.ratingdate <= TRUNC (SYSDATE)
AND iss.issuerrating NOT IN
('NR',
'WR',
'SD',
'NM',
'NRpi',
'Rpi',
'R',
'SDpi')
AND iss.spineid = x.spineid)
AS dtl_snp_rating,
(SELECT SUBSTR (MAX(TO_CHAR (ratingdate, 'YYYYMMDD')
|| iss.issuerrating),
9
FROM rating iss
WHERE iss.ratingschemeid =
(SELECT rs.ratingschemeid
FROM rating rs
WHERE rs.ratingschemename = 'MOODYS')
AND iss.ratingtypeid = (SELECT rt.ratingtypeid
FROM ratingtype rt
WHERE rt.ratingtypecode = 'LT')
AND iss.ratingdate <= TRUNC (SYSDATE)
AND iss.issuerrating NOT IN ('NR', 'WR', 'SD')
AND iss.spineid = x.spineid)
AS dtl_moodys_rating,
risk_rating AS dtl_internal_rating
FROM (SELECT /* + INDEX(xcm fvo_xcm_customer_ix3) INDEX(id fvo_ecris_d_industry_dtl_ix1)*/ xcm.customer_gci AS customer_gci,
xcm.customer_name AS customer_name,
TRIM (REPLACE (id.industry_group_name, '"', ' '))
AS industry_group_name,
id.industry_group_code,
TRIM (REPLACE (id.industry_subgroup_name, '"', ' '))
AS industry_subgroup_name,
id.industry_subgroup_code,
TRIM (REPLACE (id.industry_subgroup_name, '"', ' '))
AS dtl_industry,
(SELECT threealphacountrycode
FROM xcm_region_country_map r
WHERE r.twoalphacountrycode = xcm.country_code
AND r.regioncode != 'INTL'
AND r.region IN ('North American', 'EMEA'))
AS dtl_region,
(SELECT spineid
FROM companymap cm
WHERE cm.sourcereferenceid = 24
AND cm.sourcereferencevalue = xcm.customer_gci
AND cm.enddate IS NULL)
AS spineid,
xcm.family_gci AS family_gci,
xcm.risk_rating AS risk_rating
FROM vw_xcm xcm,
(SELECT naics_code,
industry_group_name,
industry_group_code,
industry_subgroup_name,
industry_subgroup_code
FROM vw_detail
WHERE industry_subgroup_code IS NOT NULL) id
WHERE xcm.period = (SELECT MAX (period)
FROM vw_xcm)
-- AND xcm.industry_detail_key =
-- id.industry_detail_key
AND xcm.naics_code = id.naics_code
AND TRIM (xcm.customer_gci) NOT LIKE 'S%') x
{code}Sometimes the cost-based optimizer will not take hints because it thinks it knows better. This is a matter of debate here on OTN, where some posters dogmatically assert that hints are instructions that must be followed. My experience is different. I have on rare occasions used perfectly good hints (usually INDEX) that the database simply refused to use.
Someone noted on a post a month or two ago that there may be a glitch with the CBO where it loses indexes when considering execution plans. This was based on a 10053 trace, which will show the different access paths considered during query evaluation.
Ultimately the CBO is deciding you query is more efficient not to use the indexes, even with your hint.
Looking again at your query I'll note that it is very complicated with inline views and more inline views. The CBO has trouble running multiple views efficiently - inline views, views of views, views joined to views - because views have no valid statistics associated with them. The choices the CBO makes based on views use defaults that are all but certain to be incorrect.
In particular, your index use for "id" makes no sense because it is an inline view. you could try using a global hint by pushing the hint inside the view, something like
INDEX(id.table_in_view fvo_ecris_d_industry_dtl_ix1)Unfortunately, the table inside the inline view id itself appears to be a view compliating this effort.
Try using the USE_NL hint instead of INDEX and see if that helps
Good luck -
Query takes 5 min when using Indexes and 1 Second without Indexes !!
Hi,
We have been using indexes on all tables until recently when we faced problems with queries like the one below:
SELECT a.std_id FROM students a, student_degree b, student_course c, course d
WHERE b.std_id = a.std_id
AND c.std_id = a.std_id
AND d.crn = c.crn
AND b.in_progress = 'Y'
AND b.major_code = 'ABTC'
AND a.program_code = 'DP'
AND a.level_code = 'S2'
AND a.campus_code = '05'
AND a.termcode = '200702';
This query takes more than 5 minutes to return a result, but as soon as we remove indexes on the columns termcode and campus_code,it shows result in 1 second.
What could be the problem ?, Is there an attribute that need to be set when creating these indexes ?
Thanks in advance
MadaniThank you Karthik for your reply.Here are the explain plan report (as shown on Oracle 9i Enterprise Manager)
*1-Explain plan without Indexes:*
Execution Steps:
Step # Step Name
11 SELECT STATEMENT
10 MERGE JOIN
7 SORT [JOIN]
6 NESTED LOOPS
4 NESTED LOOPS
1 ERMS.STUDENT_DEGREE TABLE ACCESS [FULL]
3 ERMS.STUDENTS TABLE ACCESS [BY INDEX ROWID]
2 ERMS.SYS_C006642 INDEX [UNIQUE SCAN]
5 ERMS.SYS_C007065 INDEX [RANGE SCAN]
9 SORT [JOIN]
8 ERMS.COURSE TABLE ACCESS [FULL]
Step # Description
1 This plan step retrieves all rows from table STUDENT_DEGREE.
2 This plan step retrieves a single ROWID from the B*-tree index SYS_C006642.
3 This plan step retrieves rows from table STUDENTS through ROWID(s) returned by an index.
4 This plan step joins two sets of rows by iterating over the driving, or outer, row set (the first child of the join) and, for each row, carrying out the steps of the inner row set (the second child). Corresponding pairs of rows are tested against the join condition specified in the query's WHERE clause.
5 This plan step retrieves one or more ROWIDs in ascending order by scanning the B*-tree index SYS_C007065.
6 This plan step joins two sets of rows by iterating over the driving, or outer, row set (the first child of the join) and, for each row, carrying out the steps of the inner row set (the second child). Corresponding pairs of rows are tested against the join condition specified in the query's WHERE clause.
7 This plan step accepts a row set (its only child) and sorts it in preparation for a merge-join operation.
8 This plan step retrieves all rows from table COURSE.
9 This plan step accepts a row set (its only child) and sorts it in preparation for a merge-join operation.
10 This plan step accepts two sets of rows sorted on the join key. By walking both sets of rows in the order of the join key, every distinct pair of rows satisfying the join condition in the WHERE clause is found through a single pass of the row sets.
11 This plan step designates this statement as a SELECT statement.
*2-Explain plan with Indexes:* (I added index on column campus_code which is a varchar2 column)
Execution Steps:
Step # Step Name
11 SELECT STATEMENT
10 MERGE JOIN
7 SORT [JOIN]
6 NESTED LOOPS
4 NESTED LOOPS
1 ERMS.COURSE TABLE ACCESS [FULL]
3 ERMS.STUDENTS TABLE ACCESS [BY INDEX ROWID]
2 ERMS.INDEX_STUDENTS_CAMPUS_CODE INDEX [RANGE SCAN]
5 ERMS.SYS_C007065 INDEX [RANGE SCAN]
9 SORT [JOIN]
8 ERMS.STUDENT_DEGREE TABLE ACCESS [FULL]
Step # Description
1 This plan step retrieves all rows from table COURSE.
2 This plan step retrieves one or more ROWIDs in ascending order by scanning the B*-tree index INDEX_STUDENTS_CAMPUS_CODE.
3 This plan step retrieves rows from table STUDENTS through ROWID(s) returned by an index.
4 This plan step joins two sets of rows by iterating over the driving, or outer, row set (the first child of the join) and, for each row, carrying out the steps of the inner row set (the second child). Corresponding pairs of rows are tested against the join condition specified in the query's WHERE clause.
5 This plan step retrieves one or more ROWIDs in ascending order by scanning the B*-tree index SYS_C007065.
6 This plan step joins two sets of rows by iterating over the driving, or outer, row set (the first child of the join) and, for each row, carrying out the steps of the inner row set (the second child). Corresponding pairs of rows are tested against the join condition specified in the query's WHERE clause.
7 This plan step accepts a row set (its only child) and sorts it in preparation for a merge-join operation.
8 This plan step retrieves all rows from table STUDENT_DEGREE.
9 This plan step accepts a row set (its only child) and sorts it in preparation for a merge-join operation.
10 This plan step accepts two sets of rows sorted on the join key. By walking both sets of rows in the order of the join key, every distinct pair of rows satisfying the join condition in the WHERE clause is found through a single pass of the row sets.
11 This plan step designates this statement as a SELECT statement. -
Oracle SGA benefits of using indexes
Goo day people,
We have been having performance issues and then the SGA was not sized coprrectely.
The size of the SGA was 720mb so we then pushed it to 4 gig which I blv is enough.
We then did a run of the tuning advisory on the top sql queries that were top one,
the advisor then pointed on that we need to use indexes on those queries .
We then advised the developers that they need to use indexes as it will improve
performance .. This morning the ADDM pointed out that we need to up the sga
to 5 Gig and I dont see this a solution to the problem.
I need to find a note on what benefits does using indexes have on the SGA and the overall perfomance
so that I can show the business that increasing the SGA wont solve the problem.
See screen shot below
erformance Finding Details:
Database Time (minutes) 33.8
Period Start Time 10-Aug-2010 10:00:11 o'clock SAST
Period Duration (minutes) 60.2
Task Owner SYS
Task Name ADDM:1511773678_1_28498
Average Active Sessions 0.6
Finding The SGA was inadequately sized, causing additional I/O or hard parses.
Impact (minutes) 14.4
Impact (%) [64] [86] 42.8
Recommendations
Show All Details | Hide All Details
Details Category Benefit (%) [Sorted in descending order]
[Select to hide information] Hide
DB Configuration [64] [86] 42.8
Action Increase the size of the SGA by setting the parameter "sga_target" to 5120 M.
Thanks
Sibusiso
Edited by: 787473 on 10-Aug-2010 02:35We have been having performance issues and then the SGA was not sized coprrectely.
The size of the SGA was 720mb so we then pushed it to 4 gig which I blv is enough.
We then did a run of the tuning advisory on the top sql queries that were top one,
the advisor then pointed on that we need to use indexes on those queries .
We then advised the developers that they need to use indexes as it will improve
performance .. Yes. As those queries must be missing indexes that would prove to be beneficial. So need to take it query by query and created the required indexes.
This morning the ADDM pointed out that we need to up the sga
to 5 Gig and I dont see this a solution to the problem.
I need to find a note on what benefits does using indexes have on the SGA and the overall perfomance
so that I can show the business that increasing the SGA wont solve the problem.
See screen shot below
erformance Finding Details:
Database Time (minutes) 33.8
Period Start Time 10-Aug-2010 10:00:11 o'clock SAST
Period Duration (minutes) 60.2
Task Owner SYS
Task Name ADDM:1511773678_1_28498
Average Active Sessions 0.6
Finding The SGA was inadequately sized, causing additional I/O or hard parses.
Impact (minutes) 14.4
Impact (%) [64] [86] 42.8
Recommendations
Show All Details | Hide All Details
Details Category Benefit (%) [Sorted in descending order]
[Select to hide information] Hide
DB Configuration [64] [86] 42.8
Action Increase the size of the SGA by setting the parameter "sga_target" to 5120 M.One of the biggest impact of indexes (if they fit in the scenario) is in reducing the IO (by avoiding full table scans). Reduced IO means faster system. Absence of indexes would mean that you read lots of data into the memory [buffer cache] and data would flush out quickly too (to make space for the new data), resulting in more IO. So having indexes in place means you only read as much amount of data as required and frequently accessed data stays in the memory.
Kinda incomplete answer...Lets wait for other experts' comments :)
Edited by: amardeep.sidhu on Aug 10, 2010 3:23 PM
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