Monday 24 November 2014

Oracle Data Pump (expdp and impdp) in Oracle Database 10g and 11g




Oracle Data Pump is a newer, faster and more flexible alternative to the "exp" and "imp" utilities used in previous Oracle versions. In addition to basic import and export functionality data pump provides a PL/SQL API and support for external tables.

Getting Started.....

For the examples to work we must first unlock the SCOTT (Not only with SCOTT you can use any schema) account and create a directory object it can access. The directory object is only a pointer to a physical directory, creating it does not actually create the physical directory on the file system of the database server.

CONN / AS SYSDBA
ALTER USER scott IDENTIFIED BY tiger ACCOUNT UNLOCK;

CREATE OR REPLACE DIRECTORY test_dir AS '/u01/app/oracle/oradata/';
GRANT READ, WRITE ON DIRECTORY test_dir TO scott;


Existing directories can be queried using the ALL_DIRECTORIES view.

Note. Data Pump is a server-based technology, so it typically deals with directory objects pointing to physical directories on the database server. It does not write to the local file system on your client PC.

Table Exports/Imports

The TABLES parameter is used to specify the tables that are to be exported. The following is an example of the table export and import syntax.

expdp scott/tiger@db10g tables=EMP,DEPT directory=TEST_DIR dumpfile=EMP_DEPT.dmp logfile=expdpEMP_DEPT.log

impdp scott/tiger@db10g tables=EMP,DEPT directory=TEST_DIR dumpfile=EMP_DEPT.dmp logfile=impdpEMP_DEPT.log
For example output files see expdpEMP_DEPT.log and impdpEMP_DEPT.log.

The TABLE_EXISTS_ACTION=APPEND parameter allows data to be imported into existing tables.

Schema Exports/Imports

the OWNER parameter of exp has been replaced by the SCHEMAS parameter which is used to specify the schemas to be exported. The following is an example of the schema export and import syntax.

expdp scott/tiger@db10g schemas=SCOTT directory=TEST_DIR dumpfile=SCOTT.dmp logfile=expdpSCOTT.log

impdp scott/tiger@db10g schemas=SCOTT directory=TEST_DIR dumpfile=SCOTT.dmp logfile=impdpSCOTT.log
For example output files see expdpSCOTT.log and impdpSCOTT.log.

Database Exports/Imports

The FULL parameter indicates that a complete database export is required. The following is an example of the full database export and import syntax.

expdp system/password@db10g full=Y directory=TEST_DIR dumpfile=DB10G.dmp logfile=expdpDB10G.log

impdp system/password@db10g full=Y directory=TEST_DIR dumpfile=DB10G.dmp logfile=impdpDB10G.log
For an example output file see expdpDB10G.log.

INCLUDE and EXCLUDE

The INCLUDE and EXCLUDE parameters can be used to limit the export/import to specific objects. When the INCLUDE parameter is used, only those objects specified by it will be included in the export/import. When the EXCLUDE parameter is used, all objects except those specified by it will be included in the export/import. The two parameters are mutually exclusive, so use the parameter that requires the least entries to give you the result you require. The basic syntax for both parameters is the same.

INCLUDE=object_type[:name_clause] [, ...]
EXCLUDE=object_type[:name_clause] [, ...]
The following code shows how they can be used as command line parameters.

expdp scott/tiger@db10g schemas=SCOTT include=TABLE:"IN ('EMP', 'DEPT')" directory=TEST_DIR dumpfile=SCOTT.dmp logfile=expdpSCOTT.log

expdp scott/tiger@db10g schemas=SCOTT exclude=TABLE:"= 'BONUS'" directory=TEST_DIR dumpfile=SCOTT.dmp logfile=expdpSCOTT.log

If the parameter is used from the command line, depending on your OS, the special characters in the clause may need to be escaped, as follows. Because of this, it is easier to use a parameter file.

include=TABLE:\"IN (\'EMP\', \'DEPT\')\"
A single import/export can include multiple references to the parameters, so to export tables, views and some packages we could use either of the following approaches.

INCLUDE=TABLE,VIEW,PACKAGE:"LIKE '%API'"

or

INCLUDE=TABLE
INCLUDE=VIEW
INCLUDE=PACKAGE:"LIKE '%API'"
Multiple objects can be targeted in once statement using the LIKE and IN operators.

EXCLUDE=SCHEMA:"LIKE 'SYS%'"

EXCLUDE=SCHEMA:"IN ('OUTLN','SYSTEM','SYSMAN','FLOWS_FILES','APEX_030200','APEX_PUBLIC_USER','ANONYMOUS')"
The valid object type paths that can be included or excluded can be displayed using the DATABASE_EXPORT_OBJECTS, SCHEMA_EXPORT_OBJECTS, and TABLE_EXPORT_OBJECTS views.

Network Exports/Imports (NETWORK_LINK)

The NETWORK_LINK parameter identifies a database link to be used as the source for a network export/import. The following database link will be used to demonstrate its use.

CONN / AS SYSDBA
GRANT CREATE DATABASE LINK TO test;

CONN test/test
CREATE DATABASE LINK remote_scott CONNECT TO scott IDENTIFIED BY tiger USING 'DEV';


In the case of exports, the NETWORK_LINK parameter identifies the database link pointing to the source server. The objects are exported from the source server in the normal manner, but written to a directory object on the local server, rather than one on the source server. Both the local and remote users require the EXP_FULL_DATABASE role granted to them.

expdp test/test@db10g tables=SCOTT.EMP network_link=REMOTE_SCOTT directory=TEST_DIR dumpfile=EMP.dmp logfile=expdpEMP.log

For imports, the NETWORK_LINK parameter also identifies the database link pointing to the source server. The difference here is the objects are imported directly from the source into the local server without being written to a dump file. Although there is no need for a DUMPFILE parameter, a directory object is still required for the logs associated with the operation. Both the local and remote users require the IMP_FULL_DATABASE role granted to them.

impdp test/test@db10g tables=SCOTT.EMP network_link=REMOTE_SCOTT directory=TEST_DIR logfile=impdpSCOTT.log remap_schema=SCOTT:TEST

Flashback Exports

The exp utility used the CONSISTENT=Y parameter to indicate the export should be consistent to a point in time. By default the expdp utility exports are only consistent on a per table basis. If you want all tables in the export to be consistent to the same point in time, you need to use the FLASHBACK_SCN or FLASHBACK_TIME parameter.

The FLASHBACK_TIME parameter value is converted to the approximate SCN for the specified time.

expdp ..... flashback_time=systimestamp

# In parameter file.
flashback_time="to_timestamp('09-05-2011 09:00:00', 'DD-MM-YYYY HH24:MI:SS')"

# Escaped on command line.
expdp ..... flashback_time=\"to_timestamp\(\'09-05-2011 09:00:00\', \'DD-MM-YYYY HH24:MI:SS\'\)\"
Not surprisingly, you can make exports consistent to an earlier point in time by specifying an earlier time or SCN, provided you have enough UNDO space to keep a read consistent view of the data during the export operation.

If you prefer to use the SCN, you can retrieve the current SCN using one of the following queries.

SELECT current_scn FROM v$database;
SELECT DBMS_FLASHBACK.get_system_change_number FROM dual;
SELECT TIMESTAMP_TO_SCN(SYSTIMESTAMP) FROM dual;


That SCN is then used with the FLASHBACK_SCN parameter.

expdp ..... flashback_scn=5474280
The following queries may prove useful for converting between timestamps and SCNs.

SELECT TIMESTAMP_TO_SCN(SYSTIMESTAMP) FROM dual;
SELECT SCN_TO_TIMESTAMP(5474751) FROM dual;
In 11.2, the introduction of legacy mode means that you can use the CONSISTENT=Y parameter with the expdp utility if you wish.

Miscellaneous Information

Unlike the original exp and imp utilities all data pump ".dmp" and ".log" files are created on the Oracle server, not the client machine.

All data pump actions are performed by multiple jobs (server processes not DBMS_JOB jobs). These jobs are controlled by a master control process which uses Advanced Queuing. At runtime an advanced queue table, named after the job name, is created and used by the master control process. The table is dropped on completion of the data pump job. The job and the advanced queue can be named using the JOB_NAME parameter. Cancelling the client process does not stop the associated data pump job. Issuing "ctrl+c" on the client during a job stops the client output and presents a command prompt. Typing "status" at this prompt allows you to monitor the current job.

Export> status

Job: SYS_EXPORT_FULL_01
  Operation: EXPORT
  Mode: FULL
  State: EXECUTING
  Bytes Processed: 0
  Current Parallelism: 1
  Job Error Count: 0
  Dump File: D:\TEMP\DB10G.DMP
    bytes written: 4,096

Worker 1 Status:
  State: EXECUTING
  Object Schema: SYSMAN
  Object Name: MGMT_CONTAINER_CRED_ARRAY
  Object Type: DATABASE_EXPORT/SCHEMA/TYPE/TYPE_SPEC
  Completed Objects: 261
  Total Objects: 261

Data pump performance can be improved by using the PARALLEL parameter. This should be used in conjunction with the "%U" wildcard in the DUMPFILE parameter to allow multiple dumpfiles to be created or read. The same wildcard can be used during the import to allow you to reference multiple files.

expdp scott/tiger@db10g schemas=SCOTT directory=TEST_DIR parallel=4 dumpfile=SCOTT_%U.dmp logfile=expdpSCOTT.log

impdp scott/tiger@db10g schemas=SCOTT directory=TEST_DIR parallel=4 dumpfile=SCOTT_%U.dmp logfile=impdpSCOTT.log

The DBA_DATAPUMP_JOBS view can be used to monitor the current jobs.

system@db10g> select * from dba_datapump_jobs;

OWNER_NAME                     JOB_NAME                       OPERATION
------------------------------ ------------------------------ ------------------------------
JOB_MODE                       STATE                              DEGREE ATTACHED_SESSIONS
------------------------------ ------------------------------ ---------- -----------------
SYSTEM                         SYS_EXPORT_FULL_01             EXPORT
FULL                           EXECUTING                               1                 1

Data Pump API

Once the job has started the status can be checked using.

system@db10g> select * from dba_datapump_jobs;




I hope this article helped you. Your suggestions/feedback are most welcome.

Keep learning... Have a great day!!!

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