Performance Tuning :: Returning All Rows That Equal Max (value)?

Oct 14, 2010

I'm trying to write a query that counts how many sessions are active during a 1 second time interval, then returns the maximum number of sessions active during any time interval, and all the time intervals that hit that max.

Here's a sample of the inner query results:

"INTERVAL_VALUE""SESSIONS"
"13:14:47" 13
"13:14:52" 13
"13:14:54" 13
"13:19:05" 4
"13:19:28" 4

[code]....

The max(sessions) is 13, so what I want the final output to be is:

"INTERVAL_VALUE""SESSIONS"
"13:14:47" 13
"13:14:52" 13
"13:14:54" 13

Here is the create sql for the test data:

CREATE TABLE "SESSION_TABLE"
(
"SESSIONKEY" NUMBER,
"SESSION_START_TIME" TIMESTAMP,
"SESSION_END_TIME" TIMESTAMP,
CONSTRAINT "PK_SESSIONKEY" PRIMARY KEY ("SESSIONKEY")
);

[code]....

Here is my query that works:

SELECT
maxval.interval_value,
allval.sessions,
licenselimit
FROM
(SELECT

[code]....

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If a table(have a primary key) is empty(after truncate),the sql of dml(insert,update) is very quickly,but if the table have many rows about 10,000,000 rows, the dml is very slowly,why?

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Jan 17, 2011

There is coulmn called DATA in a table with LONG RAW datatype. we are facing more than 60% chained rows in this table because of this LONG RAW column.

It is very difficult to clean up these chained rows periodically. Since an application using this table is a business critical interms of high availability.Hence, is there any other way in oracle to avoid chained rows permanently in future?

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1) I have 5 Exported Dump files.
2) All of those 5 dump files were taken in different time periods.
3) Many of those Dump files are having the same Partition records.

eg:-
Dump 1:- 01-06-2010 to 31-11-2010
Dump 2:- 01-09-2010 to 31-12-2010

4) Now i want to import all those partitioning data into a single table, without having any duplication.

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Performance Tuning :: Servers Will Be Running SELECT Which Returns Zero Rows All Time

Feb 11, 2011

Our application servers will be running a SELECT which returns zero rows all the time.This SELECT is put into a package and this package will be called by application servers very frequently which is causing unnecessary CPU.

Original query and plan

SQL> SELECT SEGMENT_JOB_ID, SEGMENT_SET_JOB_ID, SEGMENT_ID, TARGET_VERSION
FROM AIMUSER.SEGMENT_JOBS
WHERE SEGMENT_JOB_ID NOT IN
(SELECT SEGMENT_JOB_ID
FROM AIMUSER.SEGMENT_JOBS) 2 3 4 5 ;
[code]....

Which option will be better or do we have other options?They need to pass the column's with zero rows to a ref cursor.

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Feb 15, 2011

I am trying to update a million rows in one table with the values from another tables.

Table being updated CI_ADJ_CHAR column CHAR_VAL_FK1
Table from which values will be used CK_ADJ columns (cx_id, ci_id)

The CI_ADJ_CHAR.CHAR_VAL_FK1 values match CK_ADJ.CX_ID and should be updated with the value CK_ADJ.CI_ID.

The CK_ADJ table has 1.3 million rows and both the columns have indexes defined. Table definitiuon mentioned below

The CI_ADJ_CHAR table has 14 million rows and will update 1 million rows and has an index on the ADJ_ID column but not on the CHAR_VAL_FK1 column.

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Mar 1, 2011

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CREATE OR REPLACE PROCEDURE proc_query
DECLARE
TYPE all_dest IS TABLE OF NUMBER;
destIds all_dest;
BEGIN
SELECT dest_id from sb_packet WHERE src_id = 32;
RETURNING dest_id bulk collect into destIds;
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Oct 13, 2009

I understand what the message "subquery returning multiple rows" means but I have a case where I'm not 100% sure why it's happening to my update query (which in turn probably means I don't fully understand what's going on behind the scenes)

Here is my query:

Update A set (A.id, A.alt_name, A.min_rank)=
(SELECT B.id,
B.fullname,
MIN(B.nm_rankval)
FROM B,
A
WHERE A.id = B.id
AND A.name <> B.fullname
AND B.nametyp = 'ON'
GROUP BY B.id,
B.fullname)
;

The subquery returns 6 rows but they are all unique in terms of the id, name, rankval, etc...I naturally thought that the update statement wouldn't have a problem with this since the subquery is returning rows that are not duplicates and match one for one between table A and B. I used the group by to ensure I return unique values from table B (which does have duplicate id values)

Each of those 6 rows from the subquery of table B can be matched 1-1 with table A...so what am I missing.

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Sep 27, 2013

The following code is indicative of what I'd like to do (as in not correct at all ). Would there be a more immediate way to accomplish this other than executing a SELECT statement after the UPDATE?

-- Incorrect indicative example 1.

DECLARE
v_cur SYS_REFCURSOR;
BEGIN
UPDATE table1(f1, f2)
SET ('v1', 'v2')
WHERE f3 = 'v3'
RETURNING <updated_rows> INTO v_cur
END;

-- Incorrect indicative example 2.

DECLARE
v_cur SYS_REFCURSOR;
BEGIN
OPEN v_cur FOR
UPDATE table1(f1, f2)
SET ('v1', 'v2')
WHERE f3 = 'v3'
END;

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Mar 3, 2010

This is a surprisingly common one I've found on the web...even on devshed forum

I am updating one table from another (Updating Table A from Table B):

Table A
ID, Value
-- -----
1 A
1 A
2 B

Table B
ID, Value
-- -----
1 Animal
2 Box

Table A (modified)
ID, Value, Name
1 A Animal
1 A Animal
2 B Box

No I need to update a new column in Table A with the value in Table B.Value where the ID's from both tables match. Problem is: When I do this I get multiple rows and hence Oracle won't let me update this column. Now, I keep reading that for these types of updates, there has to be a one-to-one relationship...

Is this true...is there anyway of telling Oracle to update wherever it finds that ID, regardless of how many duplicate ID's there are?

This is quite a frustrating problem and most of the sites that I've looked for solutions try get the query one-to-one...problem is...with my table sets it's impossible to do that - I need to update wherever the id's match (even if it return multiple rows).

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--select *
select Ref_Consultant_CD
,Resident_CD
,ID
,Ref_Facility_CD
[code]......

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SQL> explain plan for MERGE /*+ parallel (rq, 16) */
INTO DWH_BILL_DET rq
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detail_rerate_flag_code,
rerate_sel_key,

[code].....

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time date,
plan number)

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Column JOB has fixed list of distinct values ('ANALYST', 'NIGHT_WORKED', etc...).

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Jun 16, 2011

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Aug 9, 2010

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For example, I have the following simple query:

select e.empid, e.ename, d.dname
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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,
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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?

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Do i need any look into any memory parameters for this?

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Oct 17, 2011

The following query gets input parameter from the Front End application, which User queries to get Reports.There are many drop down boxes like LOB, FAMILY, BRAND etc., The user may or may not select values from drop down boxes.

If the user select any one or more values ( against each drop down box) it has to fetch all matching values from DB. If the user does'nt select any values it has to fetch all the records, in this case application will send a value 'DEFAULT' (which is not a value in DB ) so that the DB will fetch all the records.

For getting this I wrote a query like below using DECODE, which colleague suggested that will hamper performance.From the below query all the variables V_ are defined in procedure which gets the values selected by user as a comma separated string here V_SELLOB and LOB_DESC is column in DB.

DECODE (V_SELLOB, 'DEFAULT', V_SELLOB, LOB_DESC) IN
OPEN v_refcursor FOR
SELECT /*+ FULL(a) PARALLEL(a, 5) */
*
FROM items a
WHERE a.sku_status = 'A'

[code]...

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Mar 17, 2012

are the most important performance keys we have to calculate or take in account to preserve or to increase the DB performance in terms of response times, and whatsoever according to performance ?

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Aug 23, 2013

I have two tables e.g. test_bb and test_sub

I would like to select test_sub.price as per the below conditions. If test_bb.value_date, test_bb.vehicle matches to test_sub.value_date,test_sub.vehicle then display test_sub.price

If there is no match then as above find the closest test_sub.value_date which is less than test_bb.value_date and select corresponding test_sub.price for the same vehicle combination.

e.g.

select * from test_sub;
VEHICLE VALUE_DAT PRICE
---------- --------- ----------
10 12-APR-12 2
10 08-JAN-10 4
10 14-APR-14 6
10 06-AUG-47 8
20 24-JAN-14 10
20 20-FEB-06 12
20 18-FEB-04 14
20 28-FEB-06 16
20 22-DEC-07 19
8 rows selected.

select * from test_bb;
VEHICLE VALUE_DAT
---------- ---------
10 12-APR-12
10 10-FEB-10
20 24-JAN-14
20 22-FEB-08

Required output:
VEHICLE PRICE VALUE_DAT
---------- ---------- ---------
10 2 12-APR-12
10 4 08-JAN-10
20 10 24-JAN-14
20 19 22-DEC-07

create table test_bb(vehicle number, value_date date);

begin
insert into test_bb values(10,to_date('12-04-2012','dd-mm-yyyy'));
insert into test_bb values(10,to_date('10-02-2010','dd-mm-yyyy'));
insert into test_bb values(20,to_date('24-01-2014','dd-mm-yyyy'));
insert into test_bb values(20,to_date('22-02-2008','dd-mm-yyyy'));
end;
/

create table test_sub(vehicle number, value_date date,price number);

begin
insert into test_sub values(10,to_date('12-04-2012','dd-mm-yyyy'),2);
insert into test_sub values(10,to_date('08-01-2010','dd-mm-yyyy'),4);
insert into test_sub values(10,to_date('14-04-2014','dd-mm-yyyy'),6);
insert into test_sub values(10,to_date('06-08-1947','dd-mm-yyyy'),8);
insert into test_sub values(20,to_date('24-01-2014','dd-mm-yyyy'),10);
insert into test_sub values(20,to_date('20-02-2006','dd-mm-yyyy'),12);
insert into test_sub values(20,to_date('18-02-2004','dd-mm-yyyy'),14);
insert into test_sub values(20,to_date('28-02-2006','dd-mm-yyyy'),16);
insert into test_sub values(20,to_date('22-DEC-2007','dd-mm-yyyy'),19);
end;
/

I could write as below but I would like to know if there is a better way of doing it.

select bb.vehicle
,sub.price
,bb.value_date
from test_bb bb
,test_sub sub
where bb.vehicle=sub.vehicle
[code].........

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I have seen that in MS SQL they have an option of arithabort which allows the database to return the rows that don't fall under the "divisor by 0".

either by setting something similar to arithabort, or maybe a procedure to check an equation and return the arithmetical steps in order that athey are performed?

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The below code gives me error (ORA-01476: divisor is equal to zero)

SELECT
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FROM WORKORDER A
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I have data

Type, Month, Amount
=========
4, 1, 43333.33333
4, 2, 43333.33333
4, 3, 43333.33333
8, 5, 16000
8, 6, 16000
8, 7, 16000
8, 8, 16000
4, 2, 100
4, 3, 100and

I want to group and SUM() equal amounts and find MIN(month) and MAX(month), so the output should look like

Type, MIN(month), MAX(month), SUM(amount)
=========
4, 1, 3, 130000
8, 5, 8, 64000
4, 2, 3, 200

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