We can use the flashback parameter ( FLASHBACK_SCN or FLASHBACK_TIMESTAMP) in expdp to take a consistent backup of the table as of a specific point in time. Flashback method depends upon undo data. So if we are trying to take an export of the table with the flashback for which data is not available in UNDO, then export will fail.

DEMO:

SQL> select count(*) from DBACLASS.OBJECT_LIST;
COUNT(*)
----------
109728

SQL> SET numwidth 20

SQL> SELECT dbms_flashback.get_system_change_number FROM DUAL;

GET_SYSTEM_CHANGE_NUMBER
------------------------
11837958118968 -- >>> We will use this SCN value in expdp

Let’s insert some new data:

SQL> insert into DBACLASS.OBJECT_LIST select * from DBACLASS.OBJECT_LIST;

109728 rows created.

SQL> commit;

SQL> SQL>  select count(*) from DBACLASS.OBJECT_LIST;

  COUNT(*)
----------
    219456
	
	

Now prepare PARFILE with FLASHBACK_SCN: ( Use the SCN value from step 1)

cat exp_flash.par

dumpfile=dbaclass.dmp
logfile=dbaclass.log
directory=EXPDIR
tables=DBACLASS.OBJECT_LIST
flashback_scn=11837958118968

expdp parfile=exp_flash.par

Export: Release 12.1.0.2.0 - Production on Mon Nov 19 12:40:59 2018

Copyright (c) 1982, 2014, Oracle and/or its affiliates.  All rights reserved.

Username: / as sysdba

Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
Starting "SYS"."SYS_EXPORT_TABLE_01":  /******** AS SYSDBA parfile=exp_flash.par
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 29 MB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/MARKER
. . exported "DBACLASS"."OBJECT_LIST"                    12.35 MB  109728 rows --- >>>> 
Master table "SYS"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYS.SYS_EXPORT_TABLE_01 is:
  /export/home/oracle/dbaclass.dmp
Job "SYS"."SYS_EXPORT_TABLE_01" successfully completed at Mon Nov 19 12:41:38 2018 elapsed 0 00:00:31


We are able to take expdp of the table with specific SCN.

Similarly, we can use FLASHBACK_TIME also:

Parfile with FLASHBACK_TIME:

 
cat exp_flash.par

dumpfile=dbaclass.dmp
logfile=dbaclass.log
directory=EXPDIR
tables=DBACLASS.OBJECT_LIST
FLASHBACK_TIME="TO_TIMESTAMP('19-11-2018 12:43:26', 'DD-MM-YYYY HH24:MI:SS')"

 expdp parfile=exp_flash.par

Export: Release 12.1.0.2.0 - Production on Mon Nov 19 12:47:36 2018

Copyright (c) 1982, 2014, Oracle and/or its affiliates.  All rights reserved.

Username: / as sysdba

Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
Starting "SYS"."SYS_EXPORT_TABLE_01":  /******** AS SYSDBA parfile=exp_flash.par
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 29 MB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type TABLE_EXPORT/TABLE/STATISTICS/MARKER
. . exported "DBACLASS"."OBJECT_LIST"                    12.35 MB  109728 rows
Master table "SYS"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYS.SYS_EXPORT_TABLE_01 is:
  /export/home/oracle/dbaclass.dmp
Job "SYS"."SYS_EXPORT_TABLE_01" successfully completed at Mon Nov 19 12:47:41 2018 elapsed 0 00:00:04