Database Reference
In-Depth Information
Data Pump Architecture
Data Pump consists of the following components:
expdp
(Data Pump export utility)
•
impdp
(Data Pump import utility)
•
DBMS_DATAPUMP
PL/SQL package (Data Pump application programming interface [API])
•
DBMS_METADATA
PL/SQL package (Data Pump Metadata API)
The
expdp
and
impdp
utilities use the
DBMS_DATAPUMP
and
DBMS_METADATA
built-in PL/SQL packages when exporting
and importing data and metadata. The
DBMS_DATAPUMP
package moves entire databases or subsets of data between
database environments. The
DBMS_METADATA
package exports and imports information about database objects.
•
■
You can call the
DBMS_DATAPUMP
and
DBMS_METADATA
packages independently (outside
expdp
and
impdp
) from
SQL*plus. I rarely call these packages directly from SQL*plus, but you may have a specific scenario in which it's desirable
to interact directly with them. See the
Oracle Database PL/SQL Packages and Types Reference Guide
, which is available
for download from the technology Network area of the Oracle Web site (
http://otn.oracle.com
)
, for more details.
Note
When you start a Data Pump export or import job, a master OS process is initiated on the database server. This
master process name has the format
ora_dmNN_<SID>
. On Linux/Unix systems, you can view this process from the OS,
prompt using the
ps
command:
$ ps -ef | grep -v grep | grep ora_dm
oracle 14602 1 4 08:59 ? 00:00:03 ora_dm00_O12C
Depending on the degree of parallelism and the work specified, a number of worker processes are also started.
If no parallelism is specified, then only one worker process is started. The master process coordinates the work
between master and worker processes. The worker process names have the format
ora_dwNN_<SID>
.
Also, when a user starts an export or import job, a database status table is created (owned by the user that starts
the job). This table exists only for the duration of the Data Pump job. The name of the status table is dependent
on what type of job you're running. The table is named with the format
SYS_<OPERATION>_<JOB_MODE>_NN
, where
OPERATION
is either
EXPORT
or
IMPORT. JOB_MODE
can be one of the following types:
•
FULL
•
SCHEMA
•
TABLE
•
TABLESPACE
•
TRANSPORTABLE
For example, if you're exporting a schema, a table is created in your account with the name
SYS_EXPORT_
SCHEMA_NN
, where
NN
is a number that makes the table name unique in the user's schema. This status table contains
information such as the objects exported/imported, start time, elapsed time, rows, and error count. The status table
has more than 80 columns.
