SQL & PL/SQL :: Query Performance In Union
Aug 10, 2010which one is better?
unloading 5 tables of same structure using a ETL tool then merging the data
using Union operator to unload 5 tables then do transformations in ETL tool
which one is better?
unloading 5 tables of same structure using a ETL tool then merging the data
using Union operator to unload 5 tables then do transformations in ETL tool
I have a SQL query where I am making UNION of two select statements. The table that I am joining in each select statement have indexes defined for those tables.
Now the UNION of the two select statements again in enclosed in an inline view , from which I fetching my final field values.
The select statements inside the inline view returns huge number of row (like 50 million rows).
The whole query fails with time out.
Is there a way to pass Oracle Hints so that Oracle uses indexes?
I have inherited a query that union alls 2 select statements, I added a further field to one of the select statements ( a date field). However I need to add another dummy field to the 2nd select statement so the union query marries up I have tried to do this by simply adding a
select
'date_on'
to add a field called date on populated by 'date_on' (the name of the column in the first query)
however when I run the union query i get the error Ora-01790 expression must have same datatype as corresponding expression.
I m looking for any other way that i can code without using union all for my case.my data example is like this
table1
--------
col1 col2 Segment1 Segment2 Segment3
-------------------------------------------------------------
A11 B11 John Jhonny Johnathan
A12 B12 Melisa Amy Abagial
I need to create view of above record as below:
table2
------
col1 col2 col3 col4
--------------------------------------------------------------
A11 B11 Segment1 John
A11 B11 Segment2 Jhonny
A11 B11 Segment3 Johnathan
A12 B12 Segment1 Melisa
A12 B12 Segment2 Amy
A12 B12 Segment3 Abagial
now my code is using UNION ALL to get output as in table2
select col1,col1,'Segment1' col3,Segment1 col4 from table1
union all
select col1,col1,'Segment2' col3,Segment2 from table1
union all
select col1,col1,'Segment3' col3,Segment3 from table1
But the problem is the performance is realy bad.Is there any way i can do this without using union all? The time that take to execute this is not exceptable.
I have a view, which has a union. (Union is required because of the nature of the data fetched). THis view is later joined with a global temp table which holds the -say employee Id the user selects.
So at runtime there is a join with the global temp table and the view. But the performance is really bad. I have tried using various hints, like materialize, /*+ CARDINALITY(gtmp 1) */ etc.
When i query the view alone,. the performance is good. When I remove the union, the performance is good. Some how with the union- there is a full table scan on one of the joining tables.
Oracle UNION ALL performance issue: when I try to run below SQL query separately SQL part1 and SQL part2 it takes some seconds only but if I run together with group by and without group by it take much time.
SELECT AVG(date_completed-login_date),to_char(to_date(login_date), 'YYYY') as wYear FROM
(
SELECT test.date_completed 'date_completed',sample.login_date 'login_date')
FROM sample test
where (some conditions) ) ---SQL part 1
UNION ALL
[code]...
We have a large customer table so first thought was to partition.Also we see two union alls in the plan - can we introduce parallelism? Below is the plan - have attached a text file if difficult to read
SELECT V_IDENTIFIER_LOOKUP.UID_V_IDENTIFIER_LOOKUP AS "UID",
V_IDENTIFIER_LOOKUP.ABA, V_IDENTIFIER_LOOKUP.ADDRESS1,
V_IDENTIFIER_LOOKUP.ADDRESS2, V_IDENTIFIER_LOOKUP.ADDRESS3,
V_IDENTIFIER_LOOKUP.ADDRESS4, V_IDENTIFIER_LOOKUP.ALIAS,
V_IDENTIFIER_LOOKUP.CITY, V_IDENTIFIER_LOOKUP.COUNTRYCODE,
V_IDENTIFIER_LOOKUP.CUST_CODE, V_IDENTIFIER_LOOKUP.CUST_NAME,
V_IDENTIFIER_LOOKUP.HEAD_OFFICE_IN,
V_IDENTIFIER_LOOKUP.IDENTIFIER,
V_IDENTIFIER_LOOKUP.IDENTIFIER_TYPE,
[code]...
this statement is taking 1hr , can we reduce the timing?
CREATE TABLE DGT_ITEMEFFORTDATA (ENTERPRISEID, OWNERTYPE, OWNERID, SUPEROWNERTYPE, SUPEROWNERID,
ITEMTYPE, ITEMID, STAGEID, USERID, DATEIDENTIFIED,
DATECLOSED, ACTIVITYCODEID, PHASEID, RELEASEID, MONTHID,
QUARTERID, INITIALEFFORT, BASELINEDEFFORT,
ACTUALEFFORT, ITEMSTATUS, ALLOCATIONSTATUS, STAGESTATUS,
OCCURANCETYPE, DSLPROJECTTYPE, METRICCALCRUNID,
[code].....
This is the explain plan of the above query
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%C
--------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 11M| 4137M| 46149 (
| 1 | UNION-ALL | | | |
| 2 | TABLE ACCESS FULL| DGT_ITEMEFFORTDATA_DAILY | 3455K| 428M| 14575
[code].....
This is the index details
1DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDITEMID4
2DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDITEMTYPE3
3DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDOWNERID2
4DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDOWNERTYPE1
There is no index on DGT_ITEMEFFORTDATA_TEMP table
[code].....
I'm just trying to see if there is another way of doing this query without using a UNION. The only way I can see is using a UNION but maybe I'm missing something or a way to do it without a UNION.
Result:
Select any customer within the user_states table who lives in "MO"
Select any customer within the user_cars table who lives in "MO" and has a "White" car
Select any customer within the user_plates table who lives in "MO" and has a plate of "A" or "B"
Join to the user_names table to display the customers name
So, the result would be any customer who lives in "MO" who owns a "White" car and any customer who lives in "MO" who has a plate of "A" or "B".
SQL
select b.customer_id,
b.first_name,
b.last_name
[Code]....
I am new to SQL Oracle programming and have a question on a union query. I am trying to get results (example) for the following:
Org # Full_date Run_date
5 2/20/2012 2/20/2012
5 2/21/2012 2/21/2012
5 2/22/2012 null (there is not a record for this)
6 2/20/2012 2/20/2012
6 2/21/2012 null
6 2/22/2012 2/22/2012
7 2/20/2012 2/20/2012
7 2/21/2012 2/21/2012
7 2/22/2012 2/22/2012
The dw_time table would have the listing of all dates, (Full_date) and the dw_capacity_daily table would have the run_date. Here is my
select * from (
select distinct a.Organization_Nbr, d.full_date
from CMBHS_DW.DW_ORGANIZATION a, cmbhs_DW.DW_Organization_Identifier b, cmbhs_DW.DW_Contract c, cmbhs_dw.dw_time d
where a.ORGANIZATION_NBR = b.ORGANIZATION_NBR
[code]....
I have one scenario in which i want to write the sql,but not able to write correct qry,
tables
1-emp
2-emp_hist
3-dept
4-dept_hist.
i want to retrieve data from the emp and hist able based on some conditions,but if data is not present in emp and dept tables.then fetch data from emp_hist and dept_hist.I have written below qry which is working fine,but my prob is i want to provide my emp_id only one place.
else i have to change my java code.
select * from emp,dept where emp.emp_id=dept.dept_id and emp_id=5
union
select * from emp_hist,dept_hist where emp_hist.emp_id=dept_hist.dept_id and emp_id=5
We have very large table having data more than 1000 millions rows. We divide this table into four physical tables say A, B, C and D. The physical horizontal partition of data of this original table is done based upon their business policy.
Each partitioned table has contained data of particular business entity. Further each table has partition and sub partitions based upon business rule.
We have to retrieve data from all these tables as follows:
select a1, a2, a3, a4, a5, a6
from A
where < logical filter condition>
union all
select b1, b2, b3, b4, b5, b6
[code].....
We observed that above each query block execute in serial one after another and individual each query block capable to process data in parallel from respective table.
How does this above query able to execute each query block in parallel?
I am an Oracle newbie.
We have 2 fact tables and one lookup table in this structure:
FACTTABLE1 (C1_ID, C2, SALE)
FACTTABLE2 (C1_ID, C3, SALE)
LOOKUPTABLE (C1_ID, C1_NAME)
The DBAs have built 2 Materialized Views, which aggregates data in the fact tables at column C1 level
MAT_VIEW1 :SELECT C1_ID, SUM(SALE) SALES from FACTTABLE1 join LOOKUPTABLE on C1_ID
MAT_VIEW2: SELECT C1_ID, SUM(SALE) SALE from FACTTABLE2 join LOOKUPTABLE on C1_ID
We are using an old BI tool that can ONLY generate Inline Views in these formats.
CASE1:
select
INL_VIEW.C1_ID
,LOOKUPTABLE.C1_NAME
,sum(SALE) SALE
from
(select C1_ID, C2_ID, null C3_ID, SALE from FACTTABLE1)INL_VIEW
join LOOKUPTABLE
on INL_VIEW.C1_ID = LOOKUPTABLE.C1_ID
group by INL_VIEW.C1_ID, LOOKUPTABLE.C1_NAME
CASE2:
select
INL_VIEW.C1_ID
,LOOKUPTABLE.C1_NAME
,sum(SALE) SALE
from
(select C1_ID, null C2_ID, C3_ID, SALE from FACTTABLE2)INL_VIEW
join LOOKUPTABLE
on INL_VIEW.C1_ID = LOOKUPTABLE.C1_ID
group by INL_VIEW.C1_ID, LOOKUPTABLE.C1_NAME
CASE3:
select
INL_VIEW.C1_ID
,LOOKUPTABLE.C1_NAME
,sum(SALE) SALE
from
(
select C1_ID, C2_ID, null C3_ID, SALE from FACTTABLE1
union all
select C1_ID, C2_ID, null C3_ID, SALE from FACTTABLE2
)INL_VIEW
join LOOKUPTABLE
on INL_VIEW.C1_ID = LOOKUPTABLE.C1_ID
group by INL_VIEW.C1_ID, LOOKUPTABLE.C1_NAME
Oracle 11g rewrites Case 1 and Case 2 to use the correct materialized views. But for case 3, it goes to the base fact tables 1 and 2. Is there a way to make oracle use the MVs even if there is a UNION ALL in the inline view? There is a 1:M Foreign Key relationship between LOOKUPTABLE.C1_ID and the 2 fact tables.
select
a.empno,a.ename,a.job,
B.DNAME
from scott.emp a,scott.dept b
where ( a.ename like 'S%' and a.deptno=b.deptno)
union
select
a.empno,a.ename,a.job,
'aaa' AS DNAME
from scott.emp a,scott.dept b
where ( a.ename like 'S%' and a.job not like 'SALES%');
Output:
7369SMITHCLERKRESEARCH
7369SMITHCLERKaaa
7788SCOTTANALYSTRESEARCH
7788SCOTTANALYSTaaa
Quote:There is other way to improve the query so that UNION can be removed.
I have a SQL query where I am making UNION of two select statements. The table that I am joining in each select statement have indexes defined for those tables.
Now the UNION of the two select statements again in enclosed in an inline view , from which I fetching my final field values.
The select statements inside the inline view returns huge number of row (like 50 million rows).
The whole query fails with time out.
How can I optimize this query further?
Is there a way to pass Oracle Hints so that Oracle uses indexes?
I am making a report in hrd regarding gross, deduction and there difference. I hv an attribute in the table as indicator whose value is addition and deduction. i want the sum of both in two diff column in a single rep. i want the report dept wise.
but i m getting fatal error at run time. which i don't understand.
I have the following Union All query. It throws the following error in SQL plus
ERROR at line 27: ORA-01789: query block has incorrect number of result columns
After doing some google for the above error it suggests there are incorrect number of columns in the Union All query.I could not figure out the exact location well SQl Plus says error is on line 27 at the first opening bracket like
(Select distinct c.contact_code
Following is the SQL query
Select
tbl_contact.contact_code,
contact_title
||'.'||contact_name contact_name,
contact_address,
[Code] ......
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?
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.
Is it better to use UNION (or) UNION ALL with DISTINCT,Which one will improve performance.
Query1:
SELECT deptno FROM emp
UNION
SELECT deptno FROM dept
Query2:
SELECT DISTINCT * FROM(SELECT deptno FROM emp
UNION ALL
SELECT deptno FROM dept)
I mean to say query1 is better (or) query2 is better,which query improves the performance.
Lot of my tables are just for join purpose , a table with just with two columns both FK , I did not add any composite PK to this table, lot my queries uses this table , because it does not have composite PK will the query be slow ? what I have to do to increase performance querying with such tables ?
View 5 Replies View RelatedI 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
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.
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?
I have a partioned (by row_create_date) table, lets called it TABLE_X, which has about 300 million records. This table has 7 columns including the primary key and a non-unique, locally partitioned column called trace_id; 99% of queries access this table via this column.
Lately, querying TABLE_X via the trace_id has been very very bad. Queries run for over 1 hr in some cases. So we decided to change the index for trace_id to a global index. Now queries against TABLE_X return in seconds. So far so good.
However, when the query has to join TABLE_X to another table, the query sometimes runs for over 1 hours; back to the same old problem. Here is an illustration;
SELECT COUNT(1) FROM TABLE_X WHERE TRACE_ID = 'XXXXX';
-- returns in seconds
SELECT COUNT(1)
FROM TABLE_X,
TABLE_Y
WHERE TABLE_X.TRACE_ID = 'XXXXX'
AND TABLE_X.TRACE_D = TABLE_Y.TRACE_ID;
-- runs for over 1 hr, even when TABLE_Y.TRACE_ID is a primary key.
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.
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]....
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?
View 3 Replies View RelatedA 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?
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 ???