Undocumented DATAPUMP parameters
10/02/2013 LEAVE A COMMENT
All the DATAPUMP supporters, I’m trying to uncover some of the ,powerful, undocumented parameters as an adduce to your argument
Below is the list of those and I’ve already written two articles about one of them i.e. TRACE
The hidden weapons I’m talking about are
Let’s see each one of them in detal
You can use the parameter METRICS=Y to include additional logging information about the number of objects and the time it took to process them in the log file.
Note that the METRICS parameter does not create any additional trace files. Instead, the extra details are logged in the logfile of the Export Data Pump or Import Data Pump job.
Here is an example:
expdp \'/ as sysdba\' DUMPFILE=dump_dir:CSM_%U.dmp SCHEMAS=CSMDBA JOB_NAME=CSM_dump METRICS=Y
Export: Release 220.127.116.11.0 - Production on Tue Dec 20 12:26:08 2011
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 18.104.22.168.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "SYS"."CSM_DUMP": "/******** AS SYSDBA" DUMPFILE=dump_dir:CSM_%U.dmp SCHEMAS=CSMDBA JOB_NAME=CSM_dump METRICS=Y
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 320 KB
Processing object type SCHEMA_EXPORT/USER
Completed 1 USER objects in 0 seconds
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Completed 1 DEFAULT_ROLE objects in 2 seconds
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Completed 1 TABLESPACE_QUOTA objects in 8 seconds
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Completed 1 PROCACT_SCHEMA objects in 27 seconds
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
. . exported "CSMDBA"."PATCH_RUN" 0 KB 0 rows
Master table "SYS"."CSM_DUMP" successfully loaded/unloaded
Dump file set for SYS.CSM_DUMP is:
Job "SYS"."CSM_DUMP" successfully completed at 10:49:19
In some situations, the undocumented parameter ACCESS_METHOD can be used to enforce a specific method to unload or load the data.
If the parameter is not specified, then Data Pump will automatically choose the best method to load or unload the data.
The parameter can only be specified when the Data Pump job is initially started i.e., the parameter cannot be specified when the job is restarted.
If the parameter is specified, the method of loading or unloading the data is enforced on all tables that need to be loaded or unloaded with the job.
Enforcing a specific method may result in a slower performance of the overall Data Pump job.
Here is an example:
expdp \'/ as sysdba\' ... ACCESS_METHOD=DIRECT_PATH
expdp \'/ as sysdba\' ... ACCESS_METHOD=EXTERNAL_TABLE
impdp \'/ as sysdba\' ... ACCESS_METHOD=DIRECT_PATH
impdp \'/ as sysdba\' ... ACCESS_METHOD=EXTERNAL_TABLE
If the undocumented DataPump parameter KEEP_MASTER=Y is used, then the Master Table is not deleted after the job completes. The drop of the master table does not lead to any data dictionary corruption and if you keep the master table after the job completes, then a drop of the master table afterwards will not cause any corruption either.
You might use this parameter if you create transportable tablespaces where the source and the destination are both ASM based.
Here is an example of the usage of this feature:
expdp \'/ as sysdba\' directory=DUMPDIR DUMPFILE=keep_master.dmp LOGFILE=keep_master.log FULL=Y KEEP_MASTER=Y