PL/SQL :: Nested Loops On Outer Joins
Apr 10, 2013
I have a select query that was working with no problems. The results are used to insert data into a temp table.
Recently, it would not complete executing. The explain plan shows a cartesian. But, there could be problems with using nested loops on the outer join.
Interestingly, when I copy production code and rename the temp table and rename the view, it works.
CREATE TABLE "CT"
( "TN" VARCHAR2(30) NOT NULL ENABLE,
"COL_NAME" VARCHAR2(30) NOT NULL ENABLE,
"CDE" VARCHAR2(5) NOT NULL ENABLE,
"CDE_DESC" VARCHAR2(80) NOT NULL ENABLE,
[Code]....
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Mar 16, 2011
What is the difference between Hash join and Nested Loops in pl / sql?
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Sep 14, 2010
10.2.0.1
I am trying to understand the concept of nested loops.
--------
| 0 | SELECT STATEMENT | | 14 | 364 | 4 (0)| 00
:00:01 |
| 1 | NESTED LOOPS | | 14 | 364 | 4 (0)| 00
:00:01 |
[Code]....
Predicate Information (identified by operation id):
---------------------------------------------------
4 - access("A"."DEPTNO"="B"."DEPTNO")
Nested loop by defintion means,for every row returned by the outer query,the inner query is executed that many times.
In the above example,oracle does a full table scan and returned 14 rows.Now for dept table,it does a index unique scan and applies the predicate a.deptno=b.deptno and returns 1 row.
My question is why it is returning only 1 row? That measn for every 14 rows,this one row is fetched 14 times.
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Oct 30, 2012
I want to make sure I am describing correctly what happens in a query where there is distributed database access and it is participating in a NESTED LOOPS JOIN. Below is an example query, the query plan output, and the remote SQL information for such a case. Of particular note are line#4 (NESTED LOOPS) and line#11 (REMOTE TABLE_0002).
What I want to know is more detail on how this NESTED LOOPS JOIN handles the remote operation. For example, for each row that comes out of line#5 and is thus going into the NESTED LOOPS JOIN operation @line#4, does the database jump across the network to do the remote loopkup? Thus if there are 1 million rows, does that mean 1 million network hops? Does batchsize play a role? For example, if the database batches in groups of 100 then does that mean 10 thousand network hops?
I think each row that comes out of line#5 means a network hop to the remote database. But I do not know for a fact.I have done some abbreviating in the plan in an attempt to make it fit on the page (line#7 TA = TABLE ACCESS).
SELECT A.POLICY ,
F.MIN_MEMBER_ID,
MIN(A.EFF_DATE) EFF_DATE,
A.EXP_DATE ,
G.DESCRIPTION PROGRAM_NAME,
[code]...
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Nov 7, 2011
I am trying to understand "ordered" hint. I want to use it in my sql where I am using some left outer joins. I believe if I use this ordered hint it will be much faster.
But the problem is I am not able to understand the concept of this hint. As i did alot of search on this eveyone says it will be , even I got some similar references where it worked But I am getting contradicting explanation for on this.
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Mar 22, 2012
these are the sample data :
CREATE OR REPLACE TYPE CourseList AS TABLE OF VARCHAR2(64);
CREATE TABLE department (
courses CourseList)
NESTED TABLE courses STORE AS courses_tab;
INSERT INTO department (courses)VALUES (CourseList('1','2','3'));
[code]....
The query returns the correct data, CourseList that are not subset of any other CourseList of the table.
I am trying to convert this not exists in a left outer join query to check if the performance is better, but I don't know how to do it.
I was making some variations of this code :
select d1.courses c_1, d2.courses c_2
from department d1,department d2
where d1.courses<>d2.courses(+);
but it is now working.
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Oct 18, 2012
I want to know how the Oracle optimizer choose joins and apply them while executing the query. So that I will insure about optimizer join before writing any query.
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Nov 21, 2011
I have a table where each record has a numerical x-coordinate value as one of its fields. I want to loop through a group of the records that have another field in common in a given order. In a nested loop, I would like to subtract the coordinate of the outer loop from the coordinate of the inner loop for all records in the inner loop that appear later in the sequence. The result is a list of the distances between all coordinates.
Example:
x-coordinate
3
4
6
7
It would look like this:
4-3, 6-3, 7-3,
6-4, 7-4,
7-6
I can do this using two nested cursors that select the same thing basically. But the table being selected from is pretty large and it takes forever to keep selecting from the huge table when the inner cursor could just copy the results of the other cursor and repeatedly iterate through them.
Is it possible to copy a cursor's results into another cursor or reset the cursor index back to the beginning so that it doesn't have to do the select statement every time?
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Aug 14, 2009
i want to know the difference between Left outer join Vs. Right outer join? Its like which join is safer to use or is there any recommendations to use any join?
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May 31, 2011
homework assignment using pl/sql based on 2 tables I have created below? I am not sure of how to use cursors, loops and proper syntax.
ASSIGNMENT:
1. Create a PL/SQL Procedure (cursor to loop through the records, check the LastName, then update the grade table
where id=id on grade table)
Rule:
A
‐ LastName ends with a character between A‐F
B
‐ LastName ends with a character between G‐K
C
‐ LastName ends with a character between L‐P
D
‐ LastName ends with a character between Q‐T
E
‐ LastName ends with a character between U‐Z
Create TABLE Registration (RegistrationID number(10), SectionID number(10), CourseID number(10),
SectionNumber varchar2(10),
StudentID number(10), FirstName varchar2(20),
LastName varchar2(20), CourseNumber varchar2(20), CourseName varchar(20));
[code].....
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Feb 25, 2012
I'm attempting to write a plsql for finding missing archived logs for streams.
requirement is to run a select statement and print
1. 'NOT FOUND' if name column is null
2. '<name of the files>' if rows are returned
3. 'NOT FOUND' if no rows are selected. (here is were i'm having trouble)
code i developed so for:
for cr in (select decode(name, NULL, 'NOT FOUND', name) from v$archived_log where deleted='YES'
and status!='A')
loop
if (cr.name = 'NOT FOUND')
[code]...
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Jan 12, 2013
i am trying to use loops to retrieve the ename of emp table of scott schema , then under they are retrieved , all "sal" values appear under them , i do not want employee's salary under each employee , i need retrieve the 14 record of enames , then under them the 14 record of sal column appears , so i used this code :
declare
cursor emp_cur is
select ename from emp;
emp_rec emp_cur%rowtype ;
[code]....
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Mar 10, 2012
Main Aim : To find all those id's who have taken all the tests within a rolling window of 45 days.
I have a table "MBS_FIRST_DATE" with the following data :This table has the patients who have the test along with the first date..This table is derived such that it has only one record with the first date of the test irrespective of the test.
create table MBS_FIRST_DATE
(
medical_record_number VARCHAR2(600),
requested_test_name VARCHAR2(39),
result_date DATE
[code]..
Process :will be explaining with a patient id :
1) Consider the patient 1001274 from mbs_first_date table.
2) This patient has an date of July 08th 2008 & test SBP from first table. (keep this test an an anchor).
3) For the patient above loop through the all_recs table with test & result date ordered for the patient. (excluding SBP)
4) The first record we have is CHL with 08/05/2009 (May 8th 2009)..
5) Since this record is not within 45 days from SBP date for the patient..we go to the next record of SBP for the patient.
6) The next record for SBP is 11/05/2009 (May 11th 2009) .
7) Consider the CHL date again which is with 08/05/2009 (May 8th 2009)..
Since both are within 45 days ..store both the values keeping SBP date as an anchor date as it's the test that's having minimum date from table 1. Even though there is one more CHL date which is within 45 days from SBP we don't care about it.
9) Go to the next test for the same patient which is DBP..
10) The DBP first date is July 08th 2008..
11) Since it's not within 45 days from previously stored SBP date (11/05/2009) ignore the record.
12) GO to the next record which is 10/05/2009..as this is within 45 days from SBP & already CHL (stored date) is within 45 days..Grab all the 3 dates as all are within 45 days from anchor date (SBP date).
SO the o/p will be
1001274 SBP 11/05/2009
1001274 CHL 08/05/2009
1001274 DBP 10/05/2009
Code which I wrote :I know some where I am missing the loop
declare
V_ID1 VARCHAR2(200) := '';
V_TEST1 VARCHAR2(200) := '';
V_DATE1 DATE := NULL;
[code]...
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Jun 17, 2008
I have a table1:
userid, name, town.
Now i want to do a self join like:
select a.name, b.name, a.town
from table1 a
inner join table1 b
on a.town = b.town
where a.first_name <> b.first_name AND
a.last_name <> b.last_name
i added the where clause to limit duplicates i would get but i still get duplicates eg. A B london, B A london etc.
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Sep 30, 2011
In mys store procedure I am using a subquery with INNER JOIN. This subquery calls a user defined function which takes main query fields as parameter values. But i am facing issue for accessing main query fields. my query is like below:
SELECT
ID, Name, sub.Desc, sub.Date
FROM MainTable main
INNER JOIN
(
SELECT * FROM RMF_GetData(main.ID)
) sub
ON main.ContactID = sub.ContactID
I need data from a function in a table format based on some case conditions. Hence i need to join it with main table. But here oracle gives error as "invalid identifier" for main.ID parameter.
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Mar 11, 2009
SELECT so.* FROM shipping_order so WHERE (so.submitter = 20)
OR (so.requestor_id IN (SELECT poc.objid FROM point_of_contact poc WHERE poc.ain = 20))
OR so.objid IN (SELECT ats.shipping_order_id FROM ac_to_so ats WHERE (ats.access_control_id IN (selectac. objid FROM access_control ac WHERE ac.ain = 20
OR ac.group IN ('buyers', 'managers'))))
rewrite this query to use joins. That would greatly simplify my sql query building code. The ids, objids, submitter, ain are numeric and group is a varchar.
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Nov 16, 2011
I pulled in 1121 SSN's into a table and am using that table as the basis for returning data from other tables...including how many documents a user has in their folder.
My query; however, is only returning 655 rows...it is returning only those rows that have documents in their folders. I want to return ALL rows...WHETHER OR NOT THEY HAVE A DOCUMENT COUNT (count(*)). How can I get all 1,121 rows to return? I would like the output to look like:
SSN LOCATION EMP_STATUS FOL_STATUS COUNT(*)
-- For those folders containing documents:
XXX-XX-XXXX WHATEVER WHATEVER WHATEVER 12
-- For those folders containing 0 documents:
XXX-XX-XXXX WHATEVER WHATEVER WHATEVER NULL
Here is the query in it's current state:
-- Get User/Folder/Doc Count Information
SELECT b.ssn,
b.location,
b.emp_status,
c.fol_status,
COUNT (*)
[Code]....
So again, my problem here is that...not all FOLDERS contain DOCUMENTS...but I still want the folder data lised...I just need it listed with either a zero count (0), or a NULL in the COUNT(*) column.
I'm trying the various joins, but none of them seem to be working.
I've tried the old 8i (+) join as follows:
AND c.fol_id = d.doc_fol_id(+)
I've tried the inner join:
AND c.fol_id(+) = d.doc_fol_id
...and I've tried the 9i method (left outer and full outer) using the following types of notations:
folder c full outer join documend d on c.fol_id = d.doc_fol_id
...so far, no luck. I'm still having only 655 rows returned (the 655 are those folders that HAVE document count > 0. Any folder that has zero documents in the document table just aren't being returned in the query.)
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May 2, 2008
why how ever way i try i cant get the joins on the tables properly.... well i know i have to work hard....if join is not proper the data i extract is also not proper.Well now i have 3 tables...
ps_operations
Name Null? Type
----------------------------------------- -------- --------
ASSB_PT_NBR_SEQ_ID NOT NULL NUMBER(8)
OPERATION_NBR NOT NULL VARCHAR2(10)
EFFECTIVE_FROM_DT NOT NULL DATE
DML_TS NOT NULL DATE
DML_USER_ID NOT NULL VARCHAR2(30)
OPERATION_DESC NOT NULL VARCHAR2(70)
HOURS_PER_PIECE_QTY NOT NULL NUMBER(9,6)
PIECES_PER_HOUR_RATE_QTY NOT NULL NUMBER(15,7)
EFFECTIVE_TO_DT DATE
EXTRACT_IND VARCHAR2(1)
[code]...
I have never worked on CPK and UK....so i dont know how to use them to join the tables,.
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Feb 23, 2012
We have access to a remote Oracle database in Germany and need to insert selected data to our local Oracle database. Our problem is that we have to do several joins (7 tables) on the remote database as well as using one where clause (always the same: P.T_LIEF_LFNT_1='12803193').
Unfortunately we do not have rights to create a view on the remote database. Is there another way to send the entire query to the remote database for processing? Also, the query returns approximately 34,000 rows.
Here is our current query:
INSERT INTO PRIMUS(PARTNO,
SORT_FORMAT,
TP_WORKSPACE,
[Code].....
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Oct 1, 2013
I have a query I am trying to tune. It presently takes anywhere from 15 minutes to two hours to run, depending on how many records the client has. But it needs to run several hundred times, and finish over the course of a weekend. When it runs over, we have problems.
Here's the basic structure of the query:
CODESELECT ...
FROM main_tab,
tab_a,
tab_b,
tab_c,
...
tab_z
WHERE main_tab.client_id = :1
AND main_tab.unique_id = tab_a.unique_id(+)
AND main_tab.unique_id = tab_b.unique_id(+)
AND main_tab.unique_id = tab_c.unique_id(+)
...
AND main_tab.unique_id = tab_z.unique_id(+);
All of the tables are indexed (and statistics are gathered) on the field unique_idMain_tab has an index on client_id.There is a one-to-one join (sometimes one-to-zero, thus the outer join) from the main_tab table to all the other tables.These are static tables, they're wiped and recreated - no changes, inserts, deletes.
By default, the optimizer does a full table scan and then a hash join on every single of the 26 tab_a through tab_z tables, only using the index on main_tab.
By the way I can add indexes, possibly even to the point of adding an index on some tables that would include all the fields found in the select clause on that table. But I cannot change the table structure (by, say, combining these tables together).
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Jan 5, 2012
I am trying to control which tables are joined based on a null value, so I figured I could use the NVL2.
Here is the code as it stands
NVL2(TBL_TRANSACTIONS.EQUIPSVCSEQ, TBL_EQUIPANDSERVICES.LASTWORKORDERSEQ, TBL_TRANSACTIONS.WORKORDERSEQ)
= TBL_WORKORDERS.WORKORDERSEQ (+)
To explain, if first value is null, then TBL_EQUIPANDSERVICES.LastWOSeq = tbl_workorders.workorderseq (+), otherwise join the transaction.workorderseq.
When I try and execute this code, I'm given "ORA-01417: a table may be outer joined to at most one other table." I've double checked, TBL_Workorders is not joined with any other table in any select.
Now, the EquipandServices.workorderseq is joined (+) with another table.
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Mar 21, 2011
can i able to partition the table based on the column which is in another table ??
For example Table X need to be partitioned based on the column in The Table Y . and Table X and table Y has some relation.
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Jul 29, 2013
i want to get SUM(salary) by combining both employee and employees table.Look my table structure below:
SQL> select * from employee;
EMPNO ENAME HIREDATE ORIG_SALARY SALARY R MGR DEPTNO
---------- --------------- --------- ----------- ---------- - ---------- ----------
1 Jason 25-JUL-96 1234 8767 E 2 10
2 John 15-JUL-97 2341 3456 W 3 20
3 Joe 25-JAN-86 4321 5654 E 3 10
4 Tom 13-SEP-06 2413 6787 W 4 20
5 Jane 17-APR-05 7654 4345 E 4 10
6 James 18-JUL-04 5679 6546 W 5 20
7 Jodd 20-JUL-03 5438 7658 E 6 10
8 Joke 01-JAN-02 8765 4543 W 20
9 Jack 29-AUG-01 7896 1232 E 10
[code]....
Above, i used separate queries to get the result of SUM(salary) by deptno.Here, I want a single query to get SUM(salary) with deptno.
deptno Sum(salary)
----------------------------
10 30056
20 27132
30 6300
40 4300
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Apr 2, 2010
I'm putting together a path to select a revision of a particular novel:
SELECT e.documentname, e.Revision, e.VersionNumber
FROM Catalog, BookInCatalog
INNER JOIN NovelMaster
INNER JOIN HasNovelRevision
INNER JOIN NovelRevision e
LEFT JOIN NovelRevision s
[code]...
My goal here is to select the earliest revision from the set of Novel revision. The revision field is a string.
When I run the query for Novels that have multiple revisions I get multiple records. If there is just one record I only get one row. If there are two I get four (two for each revision). As the number of revision increases it looks like it just mushrooms from there.
One other challenge is the format of the revision- a revision sequence could look like this:
A
B
C1
C2
C
D
E1
E
So there are "intermediate" revision referred to by a number. In this case I would select revision A, but if I had:
A1
A
B1
B
I would want to select B. I am pretty sure that all the revision are stored in the db in order.Notice that the comparison operator ">" is used in e.Revision > s.Revision. I initially though it should have been "<" because we want to select the initial but the other way gives me the right order (though the wrong results).
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Jul 31, 2012
When to use inline query and to use join.
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Sep 29, 2010
I am working on a new project in OBIEE. I am asked to do the data modeling in the database using oracle sql developer. I have to create the joins based on the requirements. I have the tables created already. But the primary keys for few tables are not defined for few tables. PK-FK joins are also not done properly.
My questions are
(1) If I have to define the primary key for the existing tables can I do that using the alter table command or should I create the table all over again and then define it?
(2) If I have to make the changes in the existing PK-FK joins how do i go about doing that?
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Feb 29, 2012
If a query can be written using where clause, what is the purpose of using joins over where clause?
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Jun 11, 2013
I am observing some skewed results for Left outer join where the main table has NULL in the field we are joining against with another table.
Just wondering if there are some tricks to get over it. I am currently using NVL(tab1.col1,'X') = NVL(tab2.col3,'X') and am just wondering if there is a better way to handle this.
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Feb 7, 2013
I want to display first joined and last joined employee name(first_name) in each department like this
department_name | first joined employee | last joined employee
I think we have to use joins and sub query.
employee table attributes -
EMPLOYEE_ID
FIRST_NAME
LAST_NAME
EMAIL
PHONE_NUMBER
HIRE_DATE
JOB_ID
[Code]....
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Apr 11, 2011
the below merge statements has outer join.
merge into merge_st t
using (select * from merge_st1) src
on (t.id=src.id(+))
when matched then update set name=src.name;
I need to convert oracle joins to ANSI joins. I have tried below
update (select t1.name as t1_name,t2.name as t2_name
from merge_st t1 lef outer join merge_st t2
on(t1.id=t2.id))
set t1_name=t2_name;
It statements shows error like cannot modify the non key preserved tables.I have cheked these table has contains whether primary key or not.there is no constraints for these tables.Our application, constaints handle in front end. so we cannot create any constraints in oracel database.how to convert oracle joins to ansi join?
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