Partitioning an existing table using datapump - a sample demo

First create a sample  table for testing purpose, 
SQL>CREATE TABLE big_table (
  id            NUMBER(10),
  created_date  DATE,
  lookup_id     NUMBER(10),
  data          VARCHAR2(50)
);

Execute the following procedure to insert large number of rows ,

DECLARE
  l_lookup_id    NUMBER(10);
  l_create_date  DATE;
BEGIN
  FOR i IN 1 .. 1000000 LOOP
    IF MOD(i, 3) = 0 THEN
      l_create_date := ADD_MONTHS(SYSDATE, -24);
      l_lookup_id   := 2;
    ELSIF MOD(i, 2) = 0 THEN
      l_create_date := ADD_MONTHS(SYSDATE, -12);
      l_lookup_id   := 1;
    ELSE
      l_create_date := SYSDATE;
      l_lookup_id   := 3;
    END IF;
    INSERT INTO big_table (id, created_date, lookup_id, data)
    VALUES (i, l_create_date, l_lookup_id, 'This is some data for ' || i);
  END LOOP;
  COMMIT;
END;
/
-- Apply some constraints and index to the table.

SQL> ALTER TABLE big_table ADD (CONSTRAINT big_table_pk PRIMARY KEY (id));

SQL>CREATE INDEX bita_created_date_i ON big_table(created_date);

Now big_table is created 

SQL>  select table_name, tablespace_name, partitioned
      from dba_tables where table_name like 'BIG_%';

TABLE_NAME                     TABLESPACE_NAME                PAR
------------------------------ ------------------------------ ---
BIG_TABLE                      EXAMPLE                        NO  ----->(No partition)

Export the table using datapump:
C:\Windows\system32>expdp admin/admin@oradb1 tables=sample.big_table directory=ar1 dumpfile=big_table.dmp parallel=4

Screen shot of my expdp:
--------------------------
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
Starting "ADMIN"."SYS_EXPORT_TABLE_01":  admin/********@oradb1 tables=sample.big_table directory=ar1 dumpfile=big_table.dmp parallel=4
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 55 MB
. . exported "SAMPLE"."BIG_TABLE"                        46.61 MB 1000000 rows
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/INDEX/INDEX
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Master table "ADMIN"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for ADMIN.SYS_EXPORT_TABLE_01 is:
  /u01/software/datapump/big_table.dmp
Job "ADMIN"."SYS_EXPORT_TABLE_01" successfully completed at 14:52:38

Now drop and recreate the table ,
SQL> drop table big_table;

Table dropped.

SQL> CREATE TABLE big_table (
    id            NUMBER(10),
    created_date  DATE,
    lookup_id     NUMBER(10),
    data          VARCHAR2(50)
)
PARTITION BY RANGE (created_date)
(PARTITION big_table_2003 VALUES LESS THAN (TO_DATE('01/01/2004', 'DD/MM/YYYY')),
 PARTITION big_table_2004 VALUES LESS THAN (TO_DATE('01/01/2005', 'DD/MM/YYYY')),
 PARTITION big_table_2005 VALUES LESS THAN (MAXVALUE));

SQL>  select table_name, tablespace_name, partitioned
      from dba_tables where table_name like 'BIG_%';

TABLE_NAME                     TABLESPACE_NAME                PAR
------------------------------ ------------------------------ ---
BIG_TABLE                      EXAMPLE                        YES ----> TABLE IS PARTITIONED

SQL> select count(*) from big_table;

  COUNT(*)
----------
         0  ----------> no data

Import the table using datapump
C:\Windows\system32> impdp admin/admin@oradb1 directory=ar1 dumpfile=big_table.dmp logfile=big_table.log table_exists_action=append parallel=4

note: job will be completed with one error because of "TABLE_EXISTS_ACTION=append" parameter.Use ignore=y if you are using old export utility.
Exclude Metadata and copy only data to avoid the error caused by the above parameter

screen shot:
-------------
Import: Release 11.2.0.1.0 - Production on Tue Jun 28 15:11:53 2011

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
Master table "ADMIN"."SYS_IMPORT_FULL_01" successfully loaded/unloaded
Starting "ADMIN"."SYS_IMPORT_FULL_01":  admin/********@oradb1 directory=ar1 dumpfile=big_table.dmp logfile=big_table.log table_exists_action=append parallel=4
Processing object type TABLE_EXPORT/TABLE/TABLE
ORA-39152: Table "SAMPLE"."BIG_TABLE" exists. Data will be appended to existing table but all dependent metadata will be skipped due to table_exists_action of append
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
. . imported "SAMPLE"."BIG_TABLE"                        46.61 MB 1000000 rows
Processing object type TABLE_EXPORT/TABLE/INDEX/INDEX
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Job "ADMIN"."SYS_IMPORT_FULL_01" completed with 1 error(s) at 15:12:49

SQL> select count(*) from big_table;

  COUNT(*)
----------
   1000000


SQL> insert into big_table (id, created_date, lookup_id, data)
  2  values(1001,'27-jun-03',5,'This is some old data');

1 row created.


SQL> select * from big_table partition(big_table_2004);

no rows selected

SQL> select * from big_table partition(big_table_2003);

        ID CREATED_D  LOOKUP_ID DATA
---------- --------- ---------- -------------------------
      1001 27-JUN-03          5 This is some old data

TESTING PARTITION PRUNING

SQL>  SET AUTOTRACE TRACEONLY EXPLAIN
SQL> select * from big_table
  2  where created_date='27-JUN-03';

Execution Plan
----------------------------------------------------------
Plan hash value: 1710340555

----------------------------------------------------------------------------------------
| Id  | Operation              | Name      | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT       |           |     1 |    37 |     3   (0)| 00:00:01 |       |       |
|   1 |  PARTITION RANGE SINGLE|           |     1 |    37 |     3   (0)| 00:00:01 |   KEY |   KEY |
|*  2 |   TABLE ACCESS FULL    | BIG_TABLE |     1 |    37 |     3   (0)| 00:00:01 |   KEY |   KEY |
----------------------------------------------------------------------------------------

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

   2 - filter("CREATED_DATE"='27-JUN-03')

Source:- http://arundaskalathil.blogspot.in/2011/06/partitioning-existing-table-using.html