ORA-06552: PL/SQL: Compilation Unit Analysis Terminated

While working today I received a strange error ORA-06552. This error I am getting while creating trigger on table. Upon R&D I came to know that this error is due to reserve word used in table column.
like:

SQL> CREATE TABLE DEMO2(TIMESTAMP TIMESTAMP);

Table created.

SQL> CREATE TABLE DEMO2_AUDIT AS SELECT * FROM DEMO2;

Table created.

SQL> ED
Wrote file afiedt.buf

  1  CREATE OR REPLACE TRIGGER demo2_trg
  2  BEFORE INSERT ON demo2
  3  FOR EACH ROW
  4  BEGIN
  5    INSERT INTO demo2_audit VALUES (:new.TIMESTAMP);
  6* END;
SQL> /
BEFORE INSERT ON demo2
                 *
ERROR at line 2:
ORA-06552: PL/SQL: Compilation unit analysis terminated
ORA-06553: PLS-320: the declaration of the type of this expression is
incomplete or malformed


SQL> SELECT * FROM V$RESERVED_WORDS WHERE KEYWORD = 'TIMESTAMP'
  2  /

KEYWORD                            LENGTH R R R R D
------------------------------ ---------- - - - - -
TIMESTAMP                               9 N N N N N

SQL> ALTER TABLE DEMO2_AUDIT  RENAME COLUMN TIMESTAMP TO TIMESTAMP2;

Table altered.

SQL> ALTER TABLE DEMO2  RENAME COLUMN TIMESTAMP TO TIMESTAMP2;

Table altered.

SQL> ED
Wrote file afiedt.buf

  1   CREATE OR REPLACE TRIGGER demo2_trg
  2   BEFORE INSERT ON demo2
  3   FOR EACH ROW
  4   BEGIN
  5     INSERT INTO demo2_audit VALUES (:new.TIMESTAMP2);
  6*  END;
SQL> /

Trigger created.

SQL>

How to log DML errors.

While performing any DML operation, if an error occurs, the statement is terminated and rolled back in its entirety. In case large DML operation it can be wasteful of time and system resources.
For such dml statements, you can avoid this situation by using the DML error logging feature.


example as:
Firstly we have to create DML error table. like

SQL> EXECUTE DBMS_ERRLOG.CREATE_ERROR_LOG('EMP', 'EMP_ERR');

PL/SQL procedure successfully completed.

SQL> DESC EMP_ERR;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ORA_ERR_NUMBER$                                    NUMBER
 ORA_ERR_MESG$                                      VARCHAR2(2000)
 ORA_ERR_ROWID$                                     ROWID
 ORA_ERR_OPTYP$                                     VARCHAR2(2)
 ORA_ERR_TAG$                                       VARCHAR2(2000)
 EMPNO                                              VARCHAR2(4000)
 ENAME                                              VARCHAR2(4000)
 JOB                                                VARCHAR2(4000)
 MGR                                                VARCHAR2(4000)
 HIREDATE                                           VARCHAR2(4000)
 SAL                                                VARCHAR2(4000)
 COMM                                               VARCHAR2(4000)
 DEPTNO                                             VARCHAR2(4000)

SQL> 

Or we can create Error log table manually.

Oracle Database logs the following errors during DML operations:
    * Column values that are too large
    * Constraint violations (NOT NULL, unique, referential, and check constraints)
    * Errors raised during trigger execution
    * Errors resulting from type conversion between a column in a subquery and the corresponding column of the table
    * Partition mapping errors
    * Certain MERGE operation errors (ORA-30926: Unable to get a stable set of rows for MERGE operation.)

Moreover some the errors will not be logged in log table as a result the DML operation will be stopped will error and roll backed.

SQL> INSERT INTO emp
  2    SELECT * FROM emp
  3    LOG ERRORS INTO EMP_ERR ('daily_load') REJECT LIMIT UNLIMITED;

0 rows created.

SQL> column ORA_ERR_MESG$ format a100
SQL> column ORA_ERR_TAG$  format  a50
SQL> column ENAME  format a50
SQL> column JOB  format a50
SQL> column SAL  format a50

SQL> select ORA_ERR_NUMBER$ ,ORA_ERR_MESG$ from emp_err;

ORA_ERR_NUMBER$ ORA_ERR_MESG$
--------------- -------------------------------------------------------------------
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated

ORA_ERR_NUMBER$ ORA_ERR_MESG$
--------------- --------------------------------------------------------------------
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated
              1 ORA-00001: unique constraint (SCOTT.PK_EMP) violated

14 rows selected.

SQL> 

Like in example insert statement doesn't fail with error.. but it has not insert any record becuase due to primary key in emp table. If we query the error log table (EMP_ERR) then we can check the error message and column values for the query is failing.

DML error logging can work on almost all dml statements (Insert, Update, Delete, Merge) This type of error logging mechanism can be very beneficial in data warehouse environments.

Also the error logging table will be transaction independent. if the base dml statement is rollback then the data which is modified in main table (EMP) will be roll backed but the error log table (EMP_ERR) table data will not be roll backed.
like:

SQL> DELETE FROM EMP_ERR;

12 rows deleted.
SQL> CREATE TABLE EMP1 AS SELECT * FROM EMP;

Table created.

SQL> UPDATE EMP1 SET EMPNO = ROWNUM WHERE ROWNUM <=2
  2  /

2 rows updated.

SQL> COMMIT;

Commit complete.

SQL> INSERT INTO EMP SELECT * FROM EMP1
  2     LOG ERRORS INTO EMP_ERR ('daily_load') REJECT LIMIT UNLIMITED;

2 rows created.

SQL> select count(*) from emp_err;

  COUNT(*)
----------
        12

SQL> select empno from emp;

    EMPNO
---------
        1
        2
     7369
     7499
     7521
     7566
     7654
     7698
     7782
     7788
     7839

    EMPNO
---------
     7844
     7876
     7900
     7902
     7934

16 rows selected.

SQL> roll
Rollback complete.
SQL> select count(*) from emp_err;

  COUNT(*)
----------
        12

SQL> select empno from emp;

    EMPNO
---------
     7369
     7499
     7521
     7566
     7654
     7698
     7782
     7788
     7839
     7844
     7876

    EMPNO
---------
     7900
     7902
     7934

14 rows selected.

SQL>

In above example after rollback changes from EMP table has been roll backed but the error messages in EMP_ERR are not rollbacked.

Find string in current schema

In some cases developer ask us to find some string in the particular schema. So, I have develop one anonymous block to find the string in tables. It will return the table name and column name in which value is existing.

SQL> SET SERVEROUTPUT ON;
SQL>
SQL> DECLARE
  2     string_to_search_v      VARCHAR(200) := UPPER('KING');
  3     datatype_V              VARCHAR(200) := 'CHAR';
  4     exists_v                NUMBER;
  5  BEGIN
  6  FOR i IN (SELECT
  7                     table_name, column_name
  8       FROM
  9             user_tab_columns
 10       WHERE
 11             data_type LIKE '%'||datatype_v||'%' AND
 12             data_length >= LENGTH(string_to_search_v) AND
 13             table_name NOT LIKE 'BIN$%' )
 14  LOOP
 15     EXECUTE IMMEDIATE 'SELECT COUNT(*) FROM ' ||i.table_name ||' WHERE UPPER('|| i.column_name
 16     ||') like ''%'|| string_to_search_v||'%'''  INTO exists_v;
 17
 18     IF exists_v > 0 THEN
 19        dbms_output.put_line ('String: ' || string_to_search_v || ' Exists in ' || i.table_name
 20        ||':'||i.column_name);
 21     END IF;
 22     END LOOP;
 23  END;
 24  /
String: KING Exists in EMP:ENAME

PL/SQL procedure successfully completed.

SQL>
SQL> 

Hope it will help.

Usage of Reserved words in object naming

Today I have been assigned to do some R&D on using Reserve words as column name or object names. When we need to use reserve words in our database when we have to use double quotes with the column/object names.

SQL> select * from v$version;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE    10.2.0.1.0      Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
SQL>
SQL>  create table demo (NUMBER number);
create table demo (NUMBER number)
*
ERROR at line 1:
ORA-00904: : invalid identifier


SQL> create table demo ("NUMBER" number);

Table created.

SQL> select NUMBER FROM DEMO;
select NUMBER FROM DEMO
*
ERROR at line 1:
ORA-00936: missing expression


SQL> select "NUMBER" FROM DEMO;

no rows selected

SQL>
SQL> insert into demo (NUMBER) values (1)
2  /
insert into demo (NUMBER) values (1)
*
ERROR at line 1:
ORA-00928: missing SELECT keyword


SQL> insert into demo ("number") values (1)
2  /
insert into demo ("number") values (1)
*
ERROR at line 1:
ORA-00904: "number": invalid identifier


SQL> insert into demo ("NUMBER") values (1)
2  /

1 row created.

SQL>

Moreover if we will use reserve words for column/table names in then we all have to support the reserve words in our ETL scripts and reporting tools also.

We can query all the reserve words with v$reserved_words dynamic view. Depending on the version oracle has different reserve words.

String to rows

SET SERVEROUTPUT ON
DECLARE
  l_list1   VARCHAR2(50) := 'A,B,C,D,E,F,G,H,I,J';
  l_list2   VARCHAR2(50);
  l_tablen  BINARY_INTEGER;
  l_tab     DBMS_UTILITY.uncl_array;
BEGIN
  DBMS_OUTPUT.put_line('l_list1 : ' || l_list1);

  DBMS_UTILITY.comma_to_table (
     list   => l_list1,
     tablen => l_tablen,
     tab    => l_tab);

  FOR i IN 1 .. l_tablen LOOP
    DBMS_OUTPUT.put_line(i || ' : ' || l_tab(i));
  END LOOP;

  DBMS_UTILITY.table_to_comma (
     tab    => l_tab,
     tablen => l_tablen,
     list   => l_list2);

  DBMS_OUTPUT.put_line('l_list2 : ' || l_list2);
END;
/

INDEX RANGE SCAN will be skipped if first character in the string to be search will be wildcard

SQL> select * from v$version;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE    10.2.0.1.0      Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production

SQL> exec dbms_stats.gather_table_stats('SCOTT','EMP',cascade=>TRUE);

PL/SQL procedure successfully completed.

First of all we are testing all the index scan without using any wild card as a first character.

SQL> set autot traceonly;
SQL> select * from emp where ename LIKE 'S%OT%T%%';


Execution Plan
----------------------------------------------------------
Plan hash value: 3307655913

---------------------------------------------------------------------------------------------
| Id  | Operation                   | Name          | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |               |     7 |   273 |     2   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP           |     7 |   273 |     2   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | EMP_ENAME_IDX |     7 |       |     1   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("ENAME" LIKE 'S%OT%T%%')
       filter("ENAME" LIKE 'S%OT%T%%')


Statistics
----------------------------------------------------------
        165  recursive calls
          0  db block gets
         30  consistent gets
          0  physical reads
          0  redo size
        826  bytes sent via SQL*Net to client
        381  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          2  sorts (memory)
          0  sorts (disk)
          1  rows processed 

Now testing using first character a wild card character.

    
SQL> set autot traceonly
SQL>  select * from emp where ename LIKE '%S%OT%T%%';


Execution Plan
----------------------------------------------------------
Plan hash value: 3956160932

--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |     1 |    39 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| EMP  |     1 |    39 |     3   (0)| 00:00:01 |
--------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter("ENAME" LIKE '%S%OT%T%%')


Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          8  consistent gets
          0  physical reads
          0  redo size
        822  bytes sent via SQL*Net to client
        381  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

It seems that whenever we are using a willcard ('%', '_') as a first character then it is skipping index scan becuase Wildchad is making the string to be search uncertain.
Let do one more experiment. Now we hide the wild card character with escape. like

SQL>  select * from emp where ename LIKE '/_S%OT%T%%' escape '/';

no rows selected


Execution Plan
----------------------------------------------------------
Plan hash value: 3307655913

---------------------------------------------------------------------------------------------
| Id  | Operation                   | Name          | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |               |     7 |   273 |     2   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP           |     7 |   273 |     2   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | EMP_ENAME_IDX |     7 |       |     1   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("ENAME" LIKE '/_S%OT%T%%' ESCAPE '/')
       filter("ENAME" LIKE '/_S%OT%T%%' ESCAPE '/')


Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          1  consistent gets
          0  physical reads
          0  redo size
        656  bytes sent via SQL*Net to client
        370  bytes received via SQL*Net from client
          1  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          0  rows processed

SQL>

CSSCAN character set scanner utilities

Basically 2 type of character set are available in Oracle. Single byte character sets and Multi-bytes character sets. Whenever we will perform character set migration from single bytes character sets to Multi-bytes character set then depending on the data size truncation can be occurred. For that case we need to increase the size of those columns. To find all those culprit columns we can use CSSCAN utility.
CSSCAN Utility Usage:
First of all we need to install CSSCAN utility. If CSSCAN utility is not installed in database the it will give following error.

C:\>
C:\>CSSCAN \"sys/*****@orcl as sysdba\" FULL=Y
Character Set Scanner v2.0 : Release 10.1.0.4.0 - Production on Wed Feb 24 13:53:44 2010
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.5.0 - Production
With the Partitioning, OLAP and Data Mining options
CSS-00107: Character set migration utility schema not installed
Scanner terminated unsuccessfully.
C:\>

If CSMIG schema is not installed then we have to run the "ORACLE_HOME/rdbms/admin/csminst.sql" as sys in sql*plus.

Character Set Scanner v2.0 : Release 10.1.0.4.0 - Production on Wed Feb 24 14:06:57 2010
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.5.0 - Production
With the Partitioning, OLAP and Data Mining options
Current database character set is AL32UTF8.
Enter new database character set name: > WE8ISO8859P1
Enter array fetch buffer size: 102400 > 
Enter number of scan processes to utilize(1..32): 1 > 32

Enumerating tables to scan...
. process 1 scanning SYS.SOURCE$[AAAABHAABAAAP6JAAA]
. process 8 scanning SYS.TAB$[AAAAACAABAAAAAZAAA]
. process 22 scanning SYS.CLU$[AAAAACAABAAAAAZAAA]
. process 24 scanning SYS.OPQTYPE$[AAAAACAABAAAAAZAAA]
. process 5 scanning SYS.ICOL$[AAAAACAABAAAAAZAAA]
. process 1 scanning SYS.LIBRARY$[AAAAACAABAAAAAZAAA]
..
..
..
..
. process 9 scanning SYS.VIEW$[AAAAA+AABAAAAHBAAA]
. process 14 scanning WK_TEST.DR$WK$DOC_PATH_IDX$I[AAAPUOAADAAAE2JAAA]
. process 17 scanning SYSMAN.MGMT_E2E_JDBC_1HOUR[AAAP2JAADAAAFPxAAA]
. process 3 scanning SYSMAN.MGMT_E2E_JDBC_1DAY[AAAP2KAADAAAFP5AAA]
. process 1 scanning SYSMAN.MGMT_BLACKOUTS[AAAP2QAADAAAFQpAAA]
. process 10 scanning SYS.USER$[AAAAAKAABAAAABZAAA]


Creating Database Scan Summary Report...
Creating Individual Exception Report...
Scanner terminated successfully.

While scanning utility will create 32 session as we have provide value 32 for 
"Enter number of scan processes to utilize(1..32): 1 >"  parameter.  
As
SQL> SELECT COUNT(*) FROM V$SESSION WHERE PROGRAM = 'csscan.exe';

  COUNT(*)
----------
        32

After completing the scan it will created 3 different files as out in file system.

Scan.txt : Database Scan Summary Report
Scan.err : Database Scan Individual Exception Report (It will contain all rows which will be truncated with its table name, cell data and rowids )
Scan.out : Scan log


CSALTER Utility to alter Database Character set

Basically two methods are available for migrating character set.

- Using Import and Export Utilities
- Using CSALTER Utility

The CSALTER script is part of the Database Character Set Scanner utility. The CSALTER script is the most straightforward way to migrate a character set, but it can be used only if all of the schema data is a strict subset of the new character set. The new character set is a strict superset of the current character set i.e. Each and every character in the current character set is available in the new character set.

CSALTER Utility will only handle CLOBs which are a part of Data Dictionary and will not handle user created CLOB.
For CSALTER Utility database Instance should be opend as restricted mode and "CLUSTER_DATABASE=FALSE" i.e. only open instance should be up in case of RAC.

SQL> SHUTDOWN IMMEDIATE
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> STARTUP RESTRICT
ORACLE instance started.

Total System Global Area  289406976 bytes
Fixed Size                  1248600 bytes
Variable Size              83886760 bytes
Database Buffers          201326592 bytes
Redo Buffers                2945024 bytes
Database mounted.
Database opened.

SQL> @@csalter.plb

0 rows created.

Function created.

Function created.

Procedure created.


This script will update the content of the Oracle Data Dictionary.
Please ensure you have a full backup before initiating this procedure.
Would you like to proceed (Y/N)?Y

old   6:     if (UPPER('&conf') <> 'Y') then
new   6:     if (UPPER('Y') <> 'Y') then

Checking data validility...

begin converting system objects

PL/SQL procedure successfully completed.

Alter the database character set...

CSALTER operation completed, please restart database

PL/SQL procedure successfully completed.

0 rows deleted.

Function dropped.

Function dropped.

Procedure dropped.

SQL>

If there will be any conversion problems then the process will report the problem and clean itself up without performing the conversion.

How to Calculate Join Cardinality

How Calculate Join Cardinality

SQL> create table tab1 as select
 2                           trunc(dbms_random.value(0,100)) col1,
 3                           chr(trunc(dbms_random.value (97, 103))) col2
 4                       from dual connect by level <= 1000;  
Table created.  

Wrote file afiedt.buf    
1  create table tab2 as select   
2                       trunc(dbms_random.value(0,1000)) col1,   
3                       chr(trunc(dbms_random.value (100, 103))) col2   
4*                    from dual connect by level <= 10000 SQL> 
/

Table created.

SQL>

Gather stats for both the tables with "For all columns size 1" with no histograms.

SQL> exec dbms_stats.gather_table_stats (ownname=>'SCOTT', tabname=>'TAB1',
 method_opt=>'for all columns size 1');

PL/SQL procedure successfully completed.

SQL> exec dbms_stats.gather_table_stats (ownname=>'SCOTT', tabname=>'TAB2', 
method_opt=>'for all columns size 1');

PL/SQL procedure successfully completed.

SQL>

SQL> ed
Wrote file afiedt.buf

 1  select count(*)
 2  from
 3     tab1,
 4     tab2
 5  where
 6     tab1.col1 = tab2.col1 and
 7*    tab1.col2 in (chr(97), chr(98), chr(99))
SQL> /

 COUNT(*)
----------
     5318


Execution Plan
----------------------------------------------------------
Plan hash value: 2043035240

----------------------------------------------------------------------------
| Id  | Operation           | Name | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------
|   0 | SELECT STATEMENT    |      |     1 |     8 |    10  (10)| 00:00:01 |
|   1 |  SORT AGGREGATE     |      |     1 |     8 |            |          |
|*  2 |   HASH JOIN         |      |  5000 | 40000 |    10  (10)| 00:00:01 |
|*  3 |    TABLE ACCESS FULL| TAB1 |   500 |  2000 |     3   (0)| 00:00:01 |
|   4 |    TABLE ACCESS FULL| TAB2 | 10000 | 40000 |     6   (0)| 00:00:01 |
----------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

  2 - access("TAB1"."COL1"="TAB2"."COL1")
  3 - filter("TAB1"."COL2"='a' OR "TAB1"."COL2"='b' OR
             "TAB1"."COL2"='c')

The forumula to calucate the Join cardinaliy as per reference from CBO Fundamentals and NoteId 68992.1 is..

Join Selectivity = 1 / max[(NDV(tab1.col1), NDV(tab2.col1)] *
((card tab1 - # tab1.col1 NULLS) / card tab1) *
((card tab2 - # tab2.col1 NULLS) / card tab2))


with the join cardinality then given as
Join Cardinality = card(tab1) * card(tab1) * sel(Pj)

Where
NDV: Number of Distinct Values
Cardinality: Number of rows
Selectivity: Proportion of a dataset returned by a particular predicate(or group of predicates)

Wrote file afiedt.buf

 1  select  TABLE_NAME, COLUMN_NAME, NUM_DISTINCT, NUM_NULLS, NUM_BUCKETS from  user_tab_col_statistics
 2* where column_name  = 'COL1'
SQL> /

TABLE_NAME                     COLUMN_NAME                    NUM_DISTINCT  NUM_NULLS NUM_BUCKETS
------------------------------ ------------------------------ ------------ ---------- -----------
TAB2                           COL1                                   1000          0           1
TAB1                           COL1                                    100          0           1

SQL>

So In our case
Join Selectivity = 1 / Max[1000,100] *
((500-0) / 500) *
((10000-0) / 10000) = 1/1000

Join Cardinality = 500 * 10000 * 1/1000 = 5000

If we match the calculated join cardinality with join cardinality in execution plan of the query it will be same.

References: Metalink Note ID: 68992.1 and Cost Based Oracle Fundamentals by Jonathan Lewis.