Regarding case in ORDER BY clause

Hi ALL,
I am having scenario that a flag value is passed ,if the falg is 'Y' ,i need to do order by with 2columns ,if the flag is 'N' no need do order by
i tried and i am able use only single column in the case statement.
Regards

select last_name,emp_no,case when sal>1000 then 'Y' else 'N' end flag
from emp
order by
case flag
when 'Y' then 1
else 2
end;
Edited by: Mahanam on Dec 20, 2010 1:13 AM

Similar Messages

Order By Clause For Retrieving Child Elements

Hi All,
I got a toplink question regarding adding an order by clause for retrieving the child elements in a 1 to many mapping.
I have an Order with a collection of Order Events. ( one to many mapping). The OrderEvent model is the super class of all events and it is abstract. The mapping for the order event descriptors has a class hierarchy mapping which uses a table for its super class (i.e OrderEvent abstract class) and different tables for its sub class elements (e.g ShippingEvent, LifeCycleEvent etc which are concrete classes).
If I add an order by clause to order the event by a spuerClassProperty in the super class descriptor, it gets ignored and the ordering is done by the alphabetic order of the indicator field values.
I also noticed that if there is more than one sub class instance for a specific class indicator value, the ordering by is observed.
I got around it with a Comparator, but just want to know if it could be possible to achieve this with toplink.
Regards.

Does the Order By appear on the SQL that get issued? TopLink only does ordering on the database, and not in memory. This means that subclass queries will be ordered per type, on not as one big list.
A Comparator is a good solution.

ViewObjects Order by clause with DECODE

Hello!
I am using Jdeveloper 11g, version 11.1.1.2.0.
The problem I'm having is this.
If I use a DECODE statement in view objects ORDER BY clause, I get an error: "java.util.regex.PatternSyntaxException: Unmatched closing ')' near index 2".
Let me give an example. I'll be using EmployeesView view object, which is using Employees entity from HR schema.
This is a part of view objects XML.
<ViewObject
xmlns="http://xmlns.oracle.com/bc4j"
Name="EmployeesView"
Version="11.1.1.55.36"
SelectList="Employees.EMPLOYEE_ID,
Employees.FIRST_NAME,
Employees.LAST_NAME,
Employees.EMAIL,
Employees.PHONE_NUMBER,
Employees.HIRE_DATE,
Employees.JOB_ID,
Employees.SALARY,
Employees.COMMISSION_PCT,
Employees.MANAGER_ID,
Employees.DEPARTMENT_ID"
FromList="EMPLOYEES Employees"
BindingStyle="OracleName"
CustomQuery="false"
PageIterMode="Full"
UseGlueCode="false"
OrderBy="Employees.MANAGER_ID">
As you can see in this case, the Order by clause is very simple. This works like a charm.
But, if put something like this "DECODE(Employees.MANAGER_ID, NULL, 1, 2)" in the Order by, I get an internal parsing error.
I replicated this error on my home machine as well as on my work machine. I'm using the same version of Jdeveloper on both.
Has anyone else stumbled upon this problem and solved it?
Any thoughts would be greatly appreciated :)
Kristjan

The second example works, but the first one doesn't, unfortunately :/
Also, the example I gave is unfortunately just that, a proof-of-concept example that there is a problem with DECODE if it is written inside the Order by clause.
My real DECODE use case is a bit different. Like this: "DECODE(attribute, 'N', 1, 2) ASC".
Since posting my original question, I did some research-by-example work and I discovered that this is not just a problem of DECODE, but more like a problem of brackets and commas.
No database function that uses more than one parameter can be used in Order by clause.
The reason is, if a function with more than one parameter is used, commas inside brackets have to be used. Something along the lines of: "database_function(param1, param2, ...)".
The parser seems to have a problem with this kind of expressions.
Is there a work around?
Kristjan
p.s.: Thank you for your quick response.

Cursor ORDER BY Clause Changing Row Count In BULK COLLECT ... FOR LOOP?

Oracle 10g Enterprise Edition Release 10.2.0.4.0 running on Windows Server 2003
Oracle Client 10.2.0.2.0 running on Windows 2000
I have some PL/SQL code that's intended to update a column in a table based on a lookup from another table. I started out by testing it with the UPDATE statement commented out, just visually inspecting the DBMS_OUTPUT results to see if it was sane. During this testing I added/changed the cursor ORDER BY clause to make it easier to read the output, and saw some strange results. I've run the code 3 times with:
1. no ORDER BY clause
2. ORDER BY with two columns (neither indexed)
3. ORDER BY with one column (not indexed)
and get three different "rows updated" counts - in fact, when using the ORDER BY clauses it appears that the code is processing more rows than without either ORDER BY clause. I'm wondering why adding / changing an ORDER BY <non-indexed column> clause in a cursor would affect the row count?
The code structure is:
TYPE my_Table_t IS TABLE OF table1%ROWTYPE ;
my_Table my_Table_t ;
CURSOR my_Cursor IS SELECT * FROM table1 ; -- initial case - no ORDER BY clause
-- ORDER BY table1.column1, table1.column2 ; -- neither column indexed
-- ORDER BY table1.column2 ; -- column not indexed
my_Loop_Count NUMBER := 0 ;
OPEN my_Cursor ;
LOOP
FETCH my_Cursor BULK COLLECT INTO my_Table LIMIT 100 ;
EXIT WHEN my_Table.COUNT = 0 ;
FOR i IN 1..my_Table.COUNT LOOP
my_New_Value := <call a pkg.funct to retrieve expected value from another table> ;
EXIT WHEN my_New_Value IS NULL ;
EXIT WHEN my_New_Value = <an undesirable value> ;
IF my_New_Value <> my_Table(i).column3 THEN
DBMS_OUTPUT.PUT_LINE( 'Changing ' || my_Table(i).column3 || ' to ' || my_New_Value ) ;
UPDATE table1 SET column3 = my_New_Value WHERE column_pk = my_Table(i).column_pk ;
my_Loop_Count := my_Loop_Count + 1 ;
END IF ;
END LOOP ;
COMMIT ;
END LOOP ;
CLOSE my_Cursor ;
DBMS_OUTPUT.PUT_LINE( 'Processed ' || my_Loop_Count || ' Rows ' ) ;

Hello (and welcome),
Your handling the inner cursor exit control is suspect, which will result in (seemingly) erratic record counts.
Instead of:
LOOP
FETCH my_Cursor BULK COLLECT INTO my_Table LIMIT 100 ;
EXIT WHEN my_Table.COUNT = 0 ;
FOR i IN 1..my_Table.COUNT LOOP
my_New_Value := <call a pkg.funct to retrieve expected value from another table> ;
EXIT WHEN my_New_Value IS NULL ;
EXIT WHEN my_New_Value = <an undesirable value> ;
IF my_New_Value my_Table(i).column3 THEN
DBMS_OUTPUT.PUT_LINE( 'Changing ' || my_Table(i).column3 || ' to ' || my_New_Value ) ;
UPDATE table1 SET column3 = my_New_Value WHERE column_pk = my_Table(i).column_pk ;
my_Loop_Count := my_Loop_Count + 1 ;
END IF ;
END LOOP ;
COMMIT ;
END LOOP ;Try this:
LOOP
FETCH my_Cursor BULK COLLECT INTO my_Table LIMIT 100 ;
FOR i IN 1..my_Table.COUNT LOOP
my_New_Value := <call a pkg.funct to retrieve expected value from another table> ;
EXIT WHEN my_New_Value IS NULL ;
EXIT WHEN my_New_Value = <an undesirable value> ;
IF my_New_Value my_Table(i).column3 THEN
DBMS_OUTPUT.PUT_LINE( 'Changing ' || my_Table(i).column3 || ' to ' || my_New_Value ) ;
UPDATE table1 SET column3 = my_New_Value WHERE column_pk = my_Table(i).column_pk ;
my_Loop_Count := my_Loop_Count + 1 ;
END IF ;
EXIT WHEN my_Cursor%NOTFOUND;
END LOOP ;
END LOOP ;
COMMIT ;Which also takes the COMMIT outside of the LOOP -- try to never have a COMMIT inside of any LOOP.
Additionally, not too sure about these:
my_New_Value := <call a pkg.funct to retrieve expected value from another table> ;
EXIT WHEN my_New_Value IS NULL ;
EXIT WHEN my_New_Value = <an undesirable value> ;Any one of those EXITs will bypass your my_Loop_Count increment.
Edited by: SeánMacGC on Jul 9, 2009 8:37 AM
Had the cursor not found in the wrong place, now corrected.

Case statement in order by clause

Hi,
I have written the below query which is having CASE statement in ORDER BY clause. Please let me know what mistake i have done in the query because am getting "Missing Keyword" Error.
SELECT opn_quest_id, seq_nbr
FROM opinion_question
order by case when :p=1 then
opn_quest_id,seq_nbr
else
opn_quest_id
end;
Thanks,
Santhosh.S

Try Ignore the following solution.
SELECT   opn_quest_id, seq_nbr
FROM   opinion_question
ORDER BY   CASE
WHEN : p = 1 THEN opn_quest_id || seq_nbr
ELSE opn_quest_id
END;
What are the data type of the corresponding columns used in the CASE Statement? I have assumed it to be strings.
!http://www.mysmiley.net/imgs/smile/sad/sad0049.gif! My Apologies....
Regards,
Jo
Edited by: Joice John on Jul 13, 2009 3:07 AM
Wrong Solution. Corrected by Sven.

Dual Case Column names fail in select ORDER BY clause

This one is solved, but I thought someone might be able to explain why it happens.
I'm a newbie, since I just downloaded Oracel XE last night, and am trying it out.
I set up a trivial table with 4 text columns. As it happened, I used dual case for some of my column names, such as 'Nickname'.
When trying out the Query Builder, the Select statement failed whenever I added a sort.
After some head scratching and back-and-forth with the sample data base (HR), I finally renamed all the columns to upper case. (e.g. column 'Nickname' became 'NICKNAME'). Then it works.
Seems like a bug, but maybe it's just a feature. Here's the code generated by the Query Builder. As you can see, there are no quotes around the Table name or column names in the ORDER BY clause (and the dual case version of the column name works if I put the quotes in manually and run it with SQL command.) Seems quirky.
select     "TEAMS"."NICKNAME" as "NICKNAME",
     "TEAMS"."CITY" as "CITY",
     "TEAMS"."DIVISION" as "DIVISION",
     "TEAMS"."CONFERENCE" as "CONFERENCE"
from     "TEAMS" "TEAMS"
order by TEAMS.NICKNAME ASC

Welcome to forum. :)
Now, answering your question - no i don't think this is a bug.
It is your code - which create this bug.
Now, question is - what happen?
Just check your select and from clause. You put all the names are in double quote. When you put anything within double quotes - it become a case sensitive. So, the problem occurs there.
Let's see ->
satyaki>
satyaki>select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Prod
PL/SQL Release 10.2.0.3.0 - Production
CORE    10.2.0.3.0      Production
TNS for 32-bit Windows: Version 10.2.0.3.0 - Production
NLSRTL Version 10.2.0.3.0 - Production
Elapsed: 00:00:01.11
satyaki>
satyaki>create table s_otn
2      (
3        id    number(4)
4      );
Table created.
Elapsed: 00:00:02.14
satyaki>
satyaki>set lin 80
satyaki>
satyaki>desc s_otn;
Name                                      Null?    Type
ID                                                 NUMBER(4)
satyaki>
satyaki>desc S_OTN;
Name                                      Null?    Type
ID                                                 NUMBER(4)
satyaki>
satyaki>desc s_OtN;
Name                                      Null?    Type
ID                                                 NUMBER(4)
satyaki>
satyaki>drop table s_otn;
Table dropped.
Elapsed: 00:00:05.22
satyaki>
satyaki>
satyaki>create table "S_otn"
2       (
3         id     number(4)
4       );
Table created.
Elapsed: 00:00:00.12
satyaki>
satyaki>
satyaki>desc S_otn;
ERROR:
ORA-04043: object S_otn does not exist
satyaki>
satyaki>desc S_OTN;
ERROR:
ORA-04043: object S_OTN does not exist
satyaki>
satyaki>desc s_otn;
ERROR:
ORA-04043: object s_otn does not exist
satyaki>
satyaki>desc "S_OTN";
ERROR:
ORA-04043: object "S_OTN" does not exist
satyaki>
satyaki>desc "S_otn";
Name                                      Null?    Type
ID                                                 NUMBER(4)
satyaki>Got me?
Regards.
Satyaki De.

CASE in an order by clause?

Can I use a case statement in an order by clause to acheive the following?
I have set up a parameter (:p_order) and placed it in a case statement in my order by clause. The idea is that the user will select a value from a LoV in the report and then dependant upon which one they picked, it will order by their selection. The problem I'm hitting is that the CASE statement seems to want to return an actual value instead of just returning the alias name to complete the order by clause. Here is the syntax I'm using:
ORDER BY
CASE WHEN :p_order = 'INVOICE NUMBER' THEN INVOICE_NUMBER
WHEN :p_order = 'INVOICE DATE' THEN INVOICE_DATE
WHEN :p_order = 'VENDOR' THEN VENDOR_NAME
WHEN :p_order = 'CHECK NUMBER' THEN CHECK_NUMBER
WHEN :p_order = 'CHECK DATE' THEN CHECK_DATE
WHEN :p_order = 'CHECK AMOUNT' THEN CHECK_AMOUNT
WHEN :p_order = 'DOA CHECK NUMBER' THEN DOA_CHECK_NUMBER
WHEN :p_order = 'DOA CHECK DATE' THEN DOA_CHECK_DATE
WHEN :p_order = 'DOA CHECK AMOUNT' THEN DOA_CHECK_AMOUNT
END
Any ideas? How can I force the case statement to return the alias name instead of a value or is that defiance in the face of what case is? Thanks!
Steve

Note, however, that if you want to dynamically choose the ORDER, you have to use dynamic SQL, not static SQL.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC

Doubt regarding multiple criteria in order by clause

Hi, I don't understand the effect of multiple elements inside the order by clause. I have the following example table:
factor_x | factor_y | price
=====================
1 | 5 | 1000
2 | 4 | 6970
3 | 3 | 3688
4 | 2 | 9087
5 | 1 | 10000
=====================
So I tried: select price from pricetable order by factor_x; results as follows:
1000
6970
3688
9087
10000
Then: select price from pricetable order by factor_y; results as follows:
10000
9087
3688
6970
1000
Then: select price from pricetable order by factor_x, factor_y; results as follows:
1000
6970
3688
9087
10000
which is same as using order by factor_x. Can anyone tells me what is the effect of adding a 2nd, 3rd..... criterion in the order by clause? Because in this example I cannot see the difference. Many thanks.

Hi,
I did a little change in your data. Hope it will help you to understand.
SQL> WITH T AS (SELECT 1 X , 1 Y , 1000 PRICE FROM DUAL UNION A
2 SELECT 2 , 4 , 6970 FROM DUAL UNION ALL
3 SELECT 4 , 3 , 3688 FROM DUAL UNION ALL
4 SELECT 4 , 2 , 9087 FROM DUAL UNION ALL
5 SELECT 4 , 5 , 10000 FROM DUAL)
6 SELECT PRICE,X,Y FROM T ORDER BY X;
     PRICE          X          Y
      1000          1          1
      6970          2          4
      9087          4          2
     10000          4          5
      3688          4          3
SQL> WITH T AS (SELECT 1 X , 1 Y , 1000 PRICE FROM DUAL UNION A
2 SELECT 2 , 4 , 6970 FROM DUAL UNION ALL
3 SELECT 4 , 3 , 3688 FROM DUAL UNION ALL
4 SELECT 4 , 2 , 9087 FROM DUAL UNION ALL
5 SELECT 4 , 5 , 10000 FROM DUAL)
6 SELECT PRICE,X,Y FROM T ORDER BY X,Y;
     PRICE          X          Y
      1000          1          1
      6970          2          4
9087 4 2
3688 4 3
10000 4 5
SQL>Regards
Avinash

Order by clause in Sub query

Hi,
Can we use order by clause in Sub query?
While using the order by clause, I am getting the "missing expression error" . If I remove order by clause query executing fine.
Here is my query:
select *
from emp_mstr
where emp_no in(select
emp_no
from emp_mstr
order by branch_no);
Thanks & Regards,
Mahi

May be you miss some required spaces also, other than wrong use of ORDER BY
select *
from emp_mstr
where emp_no in
     ( select e2.emp_no
       from emp_mstr e2
--       order by e2.branch_no
     );Why do you want to ORDER BY in the subquery, which you use with IN clause? That will not make any difference in the result..Means the result you get with ORDER BY will be same as without that.. And in this case, ORDER by is a unncessary overhead.. And Ordering is very costly..
And why do you want to have the IN clause at all in your query? You are referring the same tables in the main query and sub query..
The below will give the same result
select *
from emp_mstr
where emp_no is not nullIf you want to use another table in the subquery, always use aliasess...
select *
from emp_mstr
where emp_no in
     ( select e2.emp_no
       from emp_mstr2 e2
--       order by e2.branch_no
     );

ORDER BY Clause in XMLAGG is throwing errors.

Hi,
I'm getting errors when generating the XML using the ORDER BY clause in the XMLAgg function. Although, running the SQL directly in SQL Plus doesn't have any problem.
Here is the PL/SQL sample.
DECLARE
vX_XML SYS.XMLTYPE;
vCL_XML CLOB;
BEGIN
SELECT XMLElement("GROUP",
XMLAttributes(Group_Id AS "ID", Group_Name AS "NAME", Group_Description AS "DESC"),
XMLAgg(XMLElement("FIELD",
XMLAttributes(Field_Id AS "ID", Field_Description AS "DESC",
Table_Name AS "TAB_NM", Rule_Name AS "RULE_NM",
Field_Hierarchy_Depth AS "DOL_VAR_CALC")) ORDER BY Field_Description))
INTO vX_XML
FROM (SELECT g.Group_Id, g.Group_Name, g.Group_Description, f.Field_Id, f.Field_Description,
DECODE(f.Table_Name, 'ESTIMATES', 'E', 'LINE_ITEMS', 'L', NULL) Table_Name,
rt.Rule_Name,
CASE NVL(f.Field_Hierarchy_Depth, 0) WHEN 0 THEN 'N' ELSE 'Y' END Field_Hierarchy_Depth
FROM GROUPS g,
Rules r,
Rule_Types rt,
Fields f
WHERE g.Group_Id = 3087
AND r.Group_Id_Fk = g.Group_Id
AND rt.Rule_Type_Id = r.Rule_Type_Id_Fk
AND f.Field_Id = r.Field_Id_Fk) tab
GROUP BY Group_Id, Group_Name, Group_Description;
vCL_XML := vX_XML.GetCLOBVal();
END;
And, here are the errors.
ERROR at line 8:
ORA-06550: line 8, column 23:
PLS-00306: wrong number or types of arguments in call to 'XMLAGG'
ORA-06550: line 8, column 23:
PL/SQL: ORA-00904: "XMLAGG": invalid identifier
ORA-06550: line 6, column 5:
PL/SQL: SQL Statement ignored
Thanks in Advance.
BTW, we are using Oracle 9.2.0.4.

This is bug 2785463 with no ETA for a fix
regards
Coby D. Adams Jr.

Sorting character column ( used in order by clause dynamically)

Hi,
I need help on sorting character-based numbers. Like say, I want to sort customers based on street numbers(which is a character string being used in the
order by clause) they live in.
The criteria are :
i. Numbers must take precedence.
This being a character string, 1000001 comes before 2. This shouldn't happen. And you cannot use to_number
since using it with a string having characters in it would raise an error.
ii. If only a single alphabet occurs as the last character, then treat the whole string as a number except the last character and then sort it
as if sorting a number. Something like : if you have 1000A, 200D, 200B, 1000X, the result would be 200B,200D,1000A,1000X.
iii. if a character occurs elsewhere in the string, then perform the search normally as if performing a character search.
The output of the following data :
100
A101
B100A
110C
C120B
120
100020
120C
C1100
100D
would be like :
100
100D
110C
120
120C
100020
A101
B100A
C120B
C1100
Please note that the sort is being done dynamically, so I could have access to the values of the street numbers only during run time.
Any help is really appreciated.
Thanks in advance.
Regards,
Anil.

Create a function to test whether the column is numeric :
create FUNCTION is_numeric(v_number VARCHAR2)
RETURN INTEGER
IS
l_number NUMBER;
BEGIN
IF INSTR(UPPER(v_number),'E') > 0 THEN
RETURN 0;
END IF;
l_number := TO_NUMBER(v_number);
RETURN 1;
EXCEPTION
WHEN OTHERS THEN
RETURN 0;
END;
And try this query
Assume the table name is TEST with column STREET
select * from TEST
order by case is_numeric(STREET) when 1 then LPAD(STREET,20, ' ') else STREET end
Please make sure that 20 mentioned above is the column size for STREET.
Hope this helps.
-Nags

Problem in sql query because of order by clause

Hi All,
I am facing a one problem in my one sql query.I am using Oracle 10gR2.
Query is given below:
SELECT t1.ename
        FROM T1, T2
       WHERE T1.EMPNO = 1234
         AND T1.ACCOUNTNO = T2.ACCOUNTNO
         AND T1.SEQ = T2.SEQ
       ORDER BY T2.SEQThe Plan of the query is :
| Id | Operation                     | Name                 | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT              |                      |     2 |   218 | 11716   (1)| 00:00:41 |
|* 1 | TABLE ACCESS BY INDEX ROWID | T1                   |     1 |    89 |     1   (0)| 00:00:01 |
|   2 |   NESTED LOOPS                |                      |     2 |   218 | 11716   (1)| 00:00:41 |
|* 3 |    TABLE ACCESS BY INDEX ROWID| T2                   |     2 |    40 | 11715   (1)| 00:00:41 |
|   4 |     INDEX FULL SCAN           | PK_T2_SEQ            | 58752 |       |   122   (5)| 00:00:01 |
|* 5 |    INDEX RANGE SCAN           | FK_ACCOUNTNO         |     3 |       |     0   (0)| 00:00:01 |
----------------------------------------------------------------------------------------------------Now i want to reduce the time of this query.
If i am removing Order by clause from query than performance of the query is totally perfect but with order by clause its taking a time.
I have already set SORT_AREA_SIZE but still nothing is improving.
Welcome and thanks for your suggestions.
Thanks,
Edited by: BluShadow on 23-Jun-2011 07:55
added {noformat}{noformat} tags and formatted explain plan to make it readable. Please see {message:id=9360002} for details on how to post code and data

Hi,
There are a couple of things I do not understand.
1. Why don't you put {noformat}{noformat} around your code, it makes it so much easier to read, especially your explain plan
2. You claim that the ORDER BY is problematic compared to no order by. Then why do you choose to post only one plan?
3. It is hard to understand how your tables relate, and which indexes you have and which you don't.
- PK_T2_SEQ, does this mean that SEQ alone is primary key of T2?
- If SEQ is primary key of T2, why do you join on accountno, seq and not just seq?
- If SEQ is primary key of T2 one of the tables is denormalized.
4. FK_ACCOUNTNO, is this an index on accountno, alone?
- Or is this AccountNo, Seq?
5. Is there no index on T1.EMPNO?
Above could of course just be a case of my not understanding the names of your indexes.
So, here are my guesses:
Above plan is for the ORDER BY query. That means the optimizer, has chosen to full scan PK_T2_SEQ, since data is then read according to the ORDER BY.
(This could be a bad choice)I
You could try and order by t1.seq, instead. Result should be the same.
Regards
Peter

Problem with order by clause

Hai all,
I have problem with order by clause,
My query is
"select number from table1 order by number asc "
and the output is displaying as
1
10
12
13
15
17
19
2
20
21
22
But if we give order by it should display as below only right ?
1
2
10
12
13
15
17
19
20
21
22 ........
Please help me why it is not displaying like it. and how to make the statement to display like the second case. Thanks in advance.
Regards,
Uraja

The column datatype that you are selecting is not of NUMBER datatype(might be char or varchar2) hence you are getting such result set.
And for this purpose, it is recommended to set datatype of a column appropriately.
For now you can add TO_NUMBER function to column in ORDER BY clause, only if it has data of number type.
Edited by: Ora on 19 Nov, 2012 3:10 AM

Order By Clause - Slows performance

On 10.2 when adding an order by clause to a query affects performance that returns 6 rows of data.
Before:
select distinct col1
from table1
Cost: 3,000
Execution Time: less than a second
Chooses: Bitmap Index Fast Full Scan Index (BitMap)
After:
select distinct col1
from table1
order by col1
Cost: 14,000
Execution time: 90 seconds
Chooses: Full TableScan
Any ideas as to why the order by causes the slow down ?
Thanks,

Venzi wrote:
Now you add the order by clause to it and Oracle has now to do a sort on it. It can't sort on the BITMAP index in that case so it has to go to the table. It is possible for Oracle to do the order by through the bitmap index - the reason it doesn't is probably down to arithmetic. (The situation is made a little messier by the fact that the table and index have been parallel enabled). Here's a plan from 10.2.0.3 showing the "order by" query running through the bitmap index:
| Id | Operation                          | Name     | Rows | Bytes | Cost |    TQ |IN-OUT| PQ Distrib |
|   0 | SELECT STATEMENT                   |          |     6 |    18 |   356 |        |      |            |
|   1 | PX COORDINATOR                    |          |       |       |       |        |      |            |
|   2 |   PX SEND QC (ORDER)               | :TQ10001 |     6 |    18 |   356 | Q1,01 | P->S | QC (ORDER) |
|   3 |    SORT GROUP BY                   |          |     6 |    18 |   356 | Q1,01 | PCWP |            |
|   4 |     PX RECEIVE                     |          | 2000K| 5859K|    63 | Q1,01 | PCWP |            |
|   5 |      PX SEND RANGE                 | :TQ10000 | 2000K| 5859K|    63 | Q1,00 | P->P | RANGE      |
|   6 |       PX BLOCK ITERATOR            |          | 2000K| 5859K|    63 | Q1,00 | PCWC |            |
|   7 |        BITMAP CONVERSION TO ROWIDS |          | 2000K| 5859K|    63 | Q1,00 | PCWP |            |
|   8 |         BITMAP INDEX FAST FULL SCAN| T1_B1    |       |       |       | Q1,00 | PCWP |            |
------------------------------------------------------------------------------------------------------------Note how the optimizer can recognise that the "group by" operation will allow it to avoid an explicit "order by" operation, and uses the "(ORDER)" distribution to pass the data to the Query Coordinator to enforce correct ordering.
Running up a test case with a couple of million rows, it looks like the underlying problem the OP has is that the CBO bypasses a few of the execution options in this particular case when parallel execution is possible. (I had to hint this plan - the default plan was a serial full scan of the index that allowed the optimizer to bypass the "sort order" because of a "sort unique", but the cost was much higher than this parallel plan - see below).
| Id | Operation               | Name | Rows | Bytes | Cost |
|   0 | SELECT STATEMENT        |       |     6 |    18 | 2269 |
|   1 | SORT UNIQUE NOSORT     |       |     6 |    18 | 2269 |
|   2 |   BITMAP INDEX FULL SCAN| T1_B1 | 2000K| 5859K|   278 |
-----------------------------------------------------------------Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
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Isaac Asimov

Order by Clause is slow

Guys,
I have a table of 80,000 records.If i select * from this table need 0.04 seconds.If I add order by clause it become very slow 30 sec.
Order by clause is on the primary key.Also i increased the size of temp tablespace.
Kindly assist

In Forms, LOV's are meant for a small set of values.
For a table containing 80,000 records you need to develop a small selection form, i.e. a separate form in which you can search for values and select one value. Details for this can be acquired in the Oracle*Forms Forum. A form will typically fetch only a few rows and is therefore more suited in this case. Be sure to check the block properties "Query Array Size", "Number of Records Buffered" and "Query All Records".
At my shop we use a standard of approximately 20 values. Below this number a LOV can be used and above a select form is recommended.
Regards,
Rob.

Regarding case in ORDER BY clause

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