Oracle中impdp的TABLE_EXISTS_ACTION参数

TABLE_EXISTS_ACTION={SKIP | APPEND | TRUNCATE | REPLACE}

The possible values have the following effects:

• SKIP leaves the table as is and moves on to the next object. This is not a valid option if the CONTENT parameter is set to DATA_ONLY.

• APPEND loads rows from the source and leaves existing rows unchanged.

• TRUNCATE deletes existing rows and then loads rows from the source.

• REPLACE drops the existing table and then creates and loads it from the source. This is not a valid option if the CONTENT parameter is set to DATA_ONLY.

The following considerations apply when you are using these options:

• When you use TRUNCATE or REPLACE, make sure that rows in the affected tables are not targets of any referential constraints.

• When you use SKIP, APPEND, or TRUNCATE, existing table-dependent objects in the source, such as indexes, grants, triggers, and constraints, are ignored. For REPLACE, the dependent objects are dropped and re-created from the source, if they were not explicitly or implicitly excluded (using EXCLUDE) and they exist in the source dump file or system.

• When you use APPEND or TRUNCATE, checks are made to ensure that rows from the source are compatible with the existing table prior to performing any action.

  The existing table is loaded using the external tables access method if the existing tables have active constraints and triggers. However, be aware that if any row violates an active constraint, the load fails and no data is loaded.

  If you have data that must be loaded, but may cause constraint violations, consider disabling the constraints, loading the data, and then deleting the problem rows before reenabling the constraints.

• When you use APPEND, the data is always loaded into new space; existing space, even if available, is not reused. For this reason, you may wish to compress your data after the load.

Restrictions

• TRUNCATE cannot be used on clustered tables or over network links.

Example

The following is an example of using the TABLE_EXISTS_ACTION parameter. You can create the expfull.dmp dump file used in this example by running the example provided for the Export FULL parameter. See .

> impdp hr/hr TABLES=employees DIRECTORY=dpump_dir1 DUMPFILE=expfull.dmp TABLE_EXISTS_ACTION=REPLACE

摘自Oracle官方文档