Performance Tuning :: How To Reduce Cost Of Query
Mar 21, 2013
I have Following wjich takes some minutes to executes i want to be tune so this query Executes fast.
Query :
SELECT a.CHDR_EXCH_CD ,TMHR_EXCH_TM_CD,'S' Sec_type,
round(SUM (Decode(csdt_Depo_Typ,'I',(Cal_Scheme_Rate(csdt_rsm_code,TO_DATE(:P_DT_FR,'DD-MM-RR'),csdt_stsc_cd,csdt_scp_qty)*csdt_scp_qty)-
(Cal_Scheme_Rate(csdt_rsm_code,TO_DATE(:P_DT_FR,'DD-MM-
[Code]...
Explain Plan Result :
Plan
SELECT STATEMENT ALL_ROWS
Cost: 1,669 Bytes: 67 Cardinality: 1
15 HASH GROUP BY
Bytes: 67 Cardinality: 1
14 CONCATENATION
[Code].....
After i see result , no 4 in explain plan result gives TABLE ACCESS FULL . i want to be indexing on that how to do this..
This table MG_COLL_SCP_DTL have index like this
CREATE UNIQUE INDEX CSDT_PK ON MG_COLL_SCP_DTL
(CSDT_CHDR_TRANS_NUM, CSDT_PROD_TYP, CSDT_TRAN_SR_NO, CSDT_CHDR_CDTL_COLL_TYP, CSDT_CHDR_CDTL_COLL_TYP_CD,
CSDT_STSC_CD, CSDT_CHDR_CLNT_CD, CSDT_CHDR_CLNT_TM_CD)
[Code]....
How to Reduce cost ???
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Jun 16, 2010
I have a question about database fragmentation.I know that fragmentation can reduce performance in query times. The blocks are distributed in many extents and scans process takes a long time. Oracle engine have to locate the address of the next extent..
I want to know if there is any system view in which you can check if your table or index has high fragmentation. If it's needed I will have to re-create, move or rebulid the table or index, but before I want to know if the degree of fragmentation is high.
Any useful script or query to do this, any interesting oracle system view?
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Sep 1, 2010
For an query, cost was 16Lakhs and was taking 30min, I brought down the cost to 1.5lakhs, but still it is taking 30min.
There were many outer joins and same table has been Used(FROM clause) 5 times in the query. I have introduced WITH clause, and brought down the cost.
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Jul 23, 2010
I am facing one performance issue, in which the query cost is very low compare to cpu cost and as a result the cpu always show the high graph.I am also attaching the gv$sql and gv$sql_plan data of this query.
This is the query:
SELECT PTLS.ITEMTYPE , PTLS.ITEMID , PTLS.STAGEID, TS.USERID, SUM(PREVIOUSHOURS) AS PREVIOUSHOURS, MIN(STARTDATE) AS STARTDATE, MAX(STARTDATE) AS ENDDATE FROM PROJECTTIMELOGSSTAGE PTLS, PROJECTTIMESHEETITEM PTSI, TIMESHEET TS WHERE PTLS.PROJECTID = :B2 AND TS.TIMESHEETID = PTSI.TIMESHEETID AND TS.USERID = :B1 AND PTSI.TIMESHEETID = PTLS.TIMESHEETID AND PTSI.ITEMTYPE = PTLS.ITEMTYPE AND PTSI.ITEMID = PTLS.ITEMID AND (PTSI.ISPWFITEM = 'N' OR PTSI.ISPWFITEM IS NULL) AND PTLS.ITEMTYPE NOT IN ('OtherTsk','NewTsk','Loc','Glb') AND (PTLS.ITEMTYPE, PTLS.ITEMID ) IN (SELECT ITEMTYPE, ITEMID FROM PROJECTTIMELOGSSTAGE PTLS1 WHERE PTLS1.PROJECTID = :B2 AND PTLS1.TIMESHEETID = :B3 ) GROUP BY PTLS.ITEMTYPE, PTLS.ITEMID, PTLS.STAGEID, TS.USERID
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Aug 4, 2010
I am working on Tuning a Materialized view. I was getting an error saying ORA-12008: error in materialized view refresh path
ORA-12801: error signaled in parallel query server P002, instance hrms-stg-db01:HRSTG1 (1)
ORA-01652: unable to extend temp segment by 16 in tablespace TEMP1.
so i increased the temp size. I am trying out various hints to get it rectified. But i am not sure if i should go for less cost or less bytes.
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Jan 22, 2009
how to reduce the cpu cost for a query at query level.
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Mar 27, 2012
Following is the query on TPC-H schema.
explain plan for select
count(*)
from
orders,
lineitem
where
o_orderkey= l_orderkey.
The trace 10053 (as shown below) for this query shows nested loop join with Lineitem as outer table and Orders as inner table. It is effectively join on composite index (pk_lineitem) of Lineitem and unique index(Pk_orderkey) of Orders table. The cost calculation formula as given in the book as "outer table cost + cardinality of outer table * inner table cost " fails here. I am not able to understand this.
BASE STATISTICAL INFORMATION
***********************
Table Stats::
Table: LINEITEM Alias: LINEITEM
#Rows: 6001215 #Blks: 109048 AvgRowLen: 124.00
Column (#1): L_ORDERKEY(NUMBER)
AvgLen: 6.00 NDV: 1500000 Nulls: 0 Density: 6.6667e-07 Min: 1 Max: 6000000
[code]....
how the cost has been calculated. This does not follow the traditional nested loop cost formula as mentioned in the book.
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Jun 7, 2012
how to reduce the clustering_factor's value which appears in the user_indexes view?
in my table ,its clustering factor's value is so high:
SQL> SELECT UI.clustering_factor,UI.num_rows,UI.index_type,UI.distinct_keys FROM USER_INDEXES UI WHERE UI.table_name = 'TAWB_AWB';
CLUSTERING_FACTOR NUM_ROWS INDEX_TYPE DISTINCT_KEYS
----------------- ---------- --------------------------- -------------
83609 187603 NORMAL 187603
and its block numbers is 5063
SQL> SELECT COUNT(DISTINCT DBMS_ROWID.rowid_block_number(ROWID)) BLOCK_NUM FROM TAWB_AWB A;
BLOCK_NUM
----------
5063
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Jun 27, 2011
How can I reduce the consistent gets of the sql:
select b.OFFER_ID,
b.OFFER_CODE,
b.OFFER_NAME,
b.OFFER_COMMENTS,
b.BAND_ID,
b.CAN_BE_BUY_ALONE,
b.PRICING_PLAN_ID,
b.PRIORITY,
b.STATE,
[code]...
I have already added the indexes for the outer sql to reduce the cost from 374 to 150. But the the consistent gets seems not reduce that much. I notice that the function will cost 6 consistents gets per execution. It seems it not very high. But if this function goes with the sql, it will cost a very high consistent gets, if I remove this function, the sql only cost 1903 consistents gets.
So what I am thinking there should be two ways to reduce the consistent gets..The first one is reduce the recursive call of the sql. The second is reduce the consistent gets of the function. (but it seems that the consistent gets in this function is very low, only 6.)
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May 24, 2012
After ran db health check, my database report gives the following details
dml_locks OK. dml_locks = 3396, transactions = 849.
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Aug 17, 2010
Is there any way to reduce the index creation time. I have one table which has 7700000 records and every day this table get truncate and we create with create table as select statement and then create the 4 indexes and each index took 5 minutes so in totality it took 20 minutes in index creation.
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Nov 30, 2011
In my insert query, Window sort takes longer time i.e. 93% of total execution time, How do i reduce this time? are there any tuning parameters availabe for this?
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Aug 9, 2010
Somewhere I read that we should not use hints in Oracle production environments, but we can use hints in the development environment and on achieving the desired execution plan we can adjust the 'statistics' to follow that plan without hints.
Q1. If it is true what statistics do we adjust for influencing the execution plan and how?
For example, I have the following simple query:
select e.empid, e.ename, d.dname
from emp e, dept d
where e.deptno=d.deptno;
emp.empid, emp.deptno and dep.deptno columns have indexes and the tables have the standard structure as found in the basic oracle examples.
If I look at the execution plan of the above query then I see that the driving table is empand the driven table is dept.Also the type of join that is taking place is 'Nested Loop'.
Questions: With respect to the above query,
Q 2. If I want to make dept the driving table and emp the driven table then how can I adjust the statistics to achieve that?
Q 3. If I want to use hash join instead of a nested loop join then then how can I adjust the statistics to achieve that?
I can put the ordered and the use_hash hint to effect this but again I have heard that altering statistics is a more robust way to control an execution plan as compared to hints.
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Jun 21, 2011
I use oracle 11g r2
i have created a table for objects
create table table_t
(Record_no number,
t_no number,
position SDO_GEOMETRY
, occupation_time number);
and inserted many values (examples below )
INSERT INTO tra VALUES
(2,
20503,
SDO_GEOMETRY
(2001,
NULL,
SDO_POINT_TYPE (1387, 0, NULL),
NULL,
NULL),
23037
)
/
and( position) indexed as Rtree spatial index
now when i run spatial query such as
SELECT * FROM tra t WHERE
SDO_FILTER(t.position, MDSYS.SDO_GEOMETRY(2001,NULL,NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1,1003,3),
MDSYS.SDO_ORDINATE_ARRAY(0,0,9000,0)), 'querytype=WINDOW') = 'TRUE' and t.position.sdo_point.X=1;
i do not know how many IO accrued ?
i tried set autotrace on
but the physical read is 0 , this is not possible because i have more than 100000 objects there and all indexed as R-tree
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Jun 24, 2011
Below query is taking a long time...
select gam.SOL_ID,COUNT(gam.FORACID) from gam,smt where
gam.ACID=smt.ACID and gam.ACID NOT IN(select ACID from imt) and
gam.SCHM_TYPE in('SBA','CCA','CAA','ODA') and GAM.ACCT_CLS_FLG='N' and
gam.SOL_ID IN(select SOL_ID from IMT) group by gam.SOL_ID
/
attached is the explain plan.
in which index on IMT table is not used. And the query is doing a FTS on IMT table. What needs to be done to avoid FTS on IMT table.
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Dec 14, 2010
In SQL, almost all the thing which are possible with join is possible with sub-query also and vice-a-versa.
So when should I use sub-query and when should I go for join?
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Sep 2, 2010
I am using oracle 10g, i want to know the cost of query. In the explain plan and by auto trace am able to get some query cost, but i dont know how to calculate the query cost.
How i will know the query is costly and take more time..? But i know about the hash table and nested tables in the explain plan.
Other than this how to calculate the query cost..?
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Jan 13, 2009
Is there any way to tune the following query using lot of CPU:-select description,time_stamp,user_id from bhi_tracking where description like 'Multilateral:%'The explain plan for this is query is:-
---------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost |
----------------------------------------------------------------
| 0 | SELECT STATEMENT | | 178K| 6609K| 129K|
| 1 | TABLE ACCESS FULL| BHI_TRACKING | 178K| 6609K| 129K|
----------------------------------------------------------------
Bhi_tracking is used for reporting purpose and contain millions of records.Generally we keep one year data in this table and delete the remaining.Can I drop the table after taking export and then import it back or can i truncatethe table and then insert the rows into it to enhancethe performance.
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Dec 26, 2011
I am executing the query below:
INSERT INTO temp_vendor(vendor_record_seq_no,checksum,rownumber,transaction_type,iu_flag)
SELECT /*+ USE_NL ( vd1 ,vd2 ,vd3 ) leading ( vd1 ,vd2 ,vd3 , tvd) */ vd1.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM vendor_data vd1,
vendor_data vd2,
vendor_data vd3,
(SELECT rownumber,
[code]....
It is taking different approaches (execution plans) while executing for same set of parameters. Due to which sometimes it executes successfully, but sometimes it fills all TEMP space and get failed. I am pasting both the execution plan (different from expalin plan) below:
I. Successfull Execution Plan:
------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | | | 65612 (100)| | | |
|* 1 | HASH JOIN | | 1 | 6121 | 65612 (1)| 00:13:08 | | |
[code]....
II. Failed with TEMP space Execution Plan:
--------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
--------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | | | 1967 (100)| | | |
|* 1 | FILTER | | | | | | | |
| 2 | SORT GROUP BY | | 1 | 8233 | 1967 (3)| 00:00:24 | | |
|* 3 | HASH JOIN | | 1 | 8233 | 1966 (3)| 00:00:24 | | |
[code]....
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Jun 25, 2010
We are facing performance issues on our production instance 10g(10.2.0.4) 32-bit OELinux 5.3 2GB SGA. The performance is mainly related to one of the table which is sized about 32Gb. We have rebuild the indexes as well but problemstill persist. We are considering to pin SQL statement in shared pool which is hitting the same table frequently. But as far what we have find, is that we can only pin procedures or function in shared pool. True/false?If we can, then how to pin SQL statement in shared pool?If we can not, then is there any other way?
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Nov 27, 2012
A change(running a statistics collection package) was made, and now a query is running impossibly slow, disabling use of an application function.
This is cause by an sql , which's sql_id is know to me: 4zty77fkf907j when I run
select * from GV$SQL_PLAN_STATISTICS where SQL_ID = '4zty77fkf907j'
I get that the plan hash value is 3405747833.
I ran SELECT Q.PARSING_SCHEMA_NAME
,Q.SQL_ID,ROUND(Q.ELAPSED_TIME / Q.EXECUTIONS)/1000000 AS AVG_USECS
,Q.CHILD_NUMBER
,Q.HASH_VALUE
,Q.PLAN_HASH_VALUE
,'''' || REPLACE(Q.SQL_FULLTEXT
[code]....
and seen that the result was 2 rows(for 2 RAC nodes), with a figure of hundreds of seconds of execution, meaning - bad plan.
when I run
select * from dba_hist_sql_plan where sql_id='4zty77fkf907j'
I get plan hash value of 3390684693. I assume this might be a "good plan"
For a start, how can I hint my query to use that "good plan" before I use stored outlines to implement it?
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Oct 5, 2010
I am trying to insert data from 9i to 11g using db link with the below query but while doing so the select statement is going for a full table scan even though rowid is used. But when we execute the same select statement without this insert command it is using proper index. Similar issues I am facing for updates.
Query:
INSERT INTO /*+ APPEND */ emp@db_link
select *
from emp where rowid ='AAC2SmAIIAAAHQgAAZ'
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Aug 17, 2012
I am facing a weird situation wherein the explain plan of same sql in SIT and PROD is different.In fact the explain plan is very costly in Prod.Also the DB version of both SIT and PROD is same.
Below is the sql and corresponding explain plan in Prod and SIT respectively.
Query:
SELECT seq,CCN,ProcessorPart,root_item,comp_path,Item,comp_item,comp_item_type,
lag(comp_item_type,1,'PART') over(PARTITION BY seq ORDER BY lvl)Nxt_comp_item_type,lvl,bom_qty,
ROUND(CASE min(abs(bom_qty)) OVER (PARTITION BY seq ORDER BY lvl)
WHEN 0 THEN 0 ELSE 1 END * EXP (SUM (LN (nullif(abs(bom_qty),0))) OVER (PARTITION BY seq ORDER BY lvl))) Ulti_qty,
'AMER'
[code]...
The tables referred in above query is small tables containing arnd 10k records.The above tables are partitioned on Region and not indexed.
Explain Plan in Prod: COST CARDINALITY BYTES
SELECT STATEMENT, GOAL = ALL_ROWS165173613539322883634804
SORT UNIQUE236360
UNION-ALL
PARTITION LIST SINGLE117240
[code]...
Explain Plan in SIT: COST CARDINALITY BYTES
SELECT STATEMENT, GOAL = ALL_ROWS3211689
SORT UNIQUE347240
UNION-ALL
PARTITION LIST SINGLE172120
[code]...
I am not able to attribute why there is a huge change in Cost between SIT and Prod.Apparently the Job is going for 3-5 hours which used to get completed within 20mins in SIT.
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Sep 23, 2010
When i run a script that does a select from a single table (table has 33521868 records)the query is executed in about .094 seconds. I use the exact same query to insert into a temporary table and the query takes 10 minutes and more.
What should I be doing to speed up this process. Also tried using hints and it does not speed up the insert.
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Feb 21, 2013
I have a query optimized as to it indexes and others runs immediately when the answer is few records in SQL Server such as Oracle, however when the result is large eg 20,000 records all data access times are very diferent. The query returns many fields (about 20) and some of them are of type Varchar 250 and some of 2000 I understand here may be the problem, but not is because for similar results (20,000 records) sql run in 2 seconds and Oracle but it responds little to have full data takes around 30 seconds. The problem is really in bringing information to all these fields since if the inquiry it also but only returning a numeric field is done in 2 seconds. Tests I've done them both through ODBC, in the Toad as in the own Oracle console on the server, so it is not problem Driver or flow of data through the network, I would like to think that this is some of the settings I think there is as much difference between Oracle and Sql. The databases are ORACLE 10 and SQL Server 2008.
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Dec 8, 2010
There is a table in Database with millions of records and a query --- Select rowid, ANI, DNIS, message from tbl_sms_talkies where rownum<=:"SYS_B_0" ---- using the high CPU and also this query having high number of executions.
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Nov 11, 2012
The Item data for individual cycles is as below.
Item_tbl
ItemRundate StddateStatus
P103-Nov-1203-Nov-12A
P104-Nov-1204-Nov-12D
P2 04-Nov-1203-Nov-12A
The requirement is I have to get the details of all data of previous Active cycle(status A) when the Item became disabled(status = D) for Input date.
In above case,since for Item P1 and on cycle date 04-Nov-12,status is D,I have to consider the previous active cycle which is 03-Nov-12. Based on above std date,the data is queried from another table to get all the Items. Item P2 should not be considered in above case.
Below is the code which I have written which considers the rundate as Input parameter.
-- To get the Items disabled for Input date
with Itemdisabled as
(
select item,stddate maxcycledate
from Item_tbl
where rundate = stddate
[code]....
In above case,I'm querying the Item_tbl twice once for getting the disabled Items and once for getting the Previous cycle which is active.
Is there any way to query above only once and get the required results using Lag/Lead functions etc.
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Feb 19, 2012
How do i find a particular SQL or a set of SQL's which are excuted against a table (user identified table) that is either a very frequently executed query against that table or high impact SQL against that table? I am currently looking through the AWR reports to go through all the queries but i was wondering if there are any dictionary views where we can find this info from?
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May 5, 2011
why different elapsed time in Oracle9i and oracle10g for the same query ?
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Jun 1, 2012
I don't have any dba privileges, can you share a scripts which can tell how many block my query is fetching with or without indexes. How do i also get buffer hit, how can i get i/o without sql trace as i don't have access to dump_dest
I have a below query
SELECT DISTINCT ser_id AS STA_ser_id, rct_name AS STA_name
FROM sd_servicecalls, rep_codes, rep_codes_text
WHERE ser_sta_oid = rcd_oid
AND rcd_oid = rct_rcd_oid
AND rct_name IN ('New', 'Awaiting Approval', 'Approved', 'In Progress', 'Awaiting Supplier', 'Awaiting RFC', 'Awaiting Release', 'Pending Release', 'On Hold', 'Resolved', 'Implemented', 'Closed');
Does large hash value in explain plan mean more resource needed and more time to execute the query, How can i use ADDM for the above sql.
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