Database Reference
In-Depth Information
•
Additionally, the import job will then attempt to create any users in the export file. If a user
already exists, an error is thrown, and the import job moves on to the next task.
•
Users will be imported with the same passwords that were taken from the original database.
Depending on your security standards, you may want to change the passwords.
•
Tables will be recreated. If a table already exists and contains data, you must specify how
you want the import job to handle this. You can have the import job either skip, append,
replace, or truncate the table (see the section “Importing When Objects Already Exist,” later
in this chapter).
•
After each table is created and populated, associated indexes are created.
•
The import job will also try to import statistics if available. Furthermore, object grants are
instantiated.
If everything runs well, the end result will be a database that is logically identical to the source database in terms
of tablespaces, users, objects, and so on.
Schema Level
When you initiate an export, unless otherwise specified, Data Pump starts a schema-level export for the user running
the export job. User-level exports are frequently used to copy a schema or set of schemas from one environment to
another. The following command starts a schema-level export for the
MV_MAINT
user:
$ expdp mv_maint/foo directory=dp_dir dumpfile=mv_maint.dmp logfile=mv_maint.log
In the output displayed on the screen, you should see some text indicating that a schema-level export has been
initiated:
Starting "MV_MAINT"."SYS_EXPORT_SCHEMA_01"...
You can also initiate a schema-level export for users other than the one running the export job with the
SCHEMAS
parameter. The following command shows a schema-level export for multiple users:
$ expdp mv_maint/foo directory=dp_dir dumpfile=user.dmp schemas=heera,chaya
You can initiate a schema-level import by referencing a dump file that was taken with a schema-level export:
$ impdp mv_maint/foo directory=dp_dir dumpfile=user.dmp
When you initiate a schema-level import, there are some details to be aware of:
•
No tablespaces are included in a schema-level export.
•
The import job attempts to recreate any users in the dump file. If a user already exists, an error
is thrown, and the import job continues.
•
The import job will reset the users' passwords, based on the password that was exported.
•
Tables owned by the users will be imported and populated. If a table already exists, you must
instruct Data Pump on how to handle this with the
TABLE_EXISTS_ACTION
parameter.
