Data Pump 10g / 11g Flashback_Scn and flashback_Time parameter

Flashback Exports 10g

The exp utility used the CONSISTENT=Y parameter to indicate the export should be consistent to a point in time. By default the expdp utility exports are only consistent on a per table basis. If you want all tables in the export to be consistent to the same point in time, you need to use the FLASHBACK_SCN or FLASHBACK_TIME parameter.
The FLASHBACK_TIME parameter value is converted to the approximate SCN for the specified time.

expdp ..... flashback_time=systimestamp

# In parameter file.

flashback_time="to_timestamp('09-05-2011 09:00:00', 'DD-MM-YYYY HH24:MI:SS')"

# Escaped on command line.

expdp ..... flashback_time=\"to_timestamp\(\'09-05-2011 09:00:00\', \'DD-MM-YYYY HH24:MI:SS\'\)\"

Not surprisingly, you can make exports consistent to an earlier point in time by specifying an earlier time or SCN, provided you have enough UNDO space to keep a read consistent view of the data during the export operation.
If you prefer to use the SCN, you can retrieve the current SCN using one of the following queries.

SELECT current_scn FROM v$database;

SELECT DBMS_FLASHBACK.get_system_change_number FROM dual;

SELECT TIMESTAMP_TO_SCN(SYSTIMESTAMP) FROM dual;

That SCN is then used with the FLASHBACK_SCN parameter.

expdp ..... flashback_scn=5474280

The following queries may prove useful for converting between timestamps and SCNs.

SELECT TIMESTAMP_TO_SCN(SYSTIMESTAMP) FROM dual;

SELECT SCN_TO_TIMESTAMP(5474751) FROM dual;

In 11.2, the introduction of legacy mode means that you can use the CONSISTENT=Y parameter with the expdp utility if you wish.

If you want to use a parameter file, you should make a file with for example this content and give it for example the name scott.par:

schemas=scott
dumpfile=exp_scott.dmp
logfile=exp_scott.log
directory=DATA_PUMP_DIR
flashback_time=systimestamp
..

You then can execute the export using:


expdp system/password parfile=scott.par

If you want a time consistent export on another timestamp, let say september 3rd 2014 on 14:41:00 then you should set the flashback_time parameter as follows:


flashback_time=”to_timestamp(’03-09-2014 14:41:00′, ‘DD-MM-YYYY HH24:MI:SS’)”


11g  ver: - 11.1

Flashback_Scn  and  flashback_Time  are  two  important  feature  of  the  datapump 11g . If  we  want  to  run  a  large  export  whilst  the  database  is  in  use  then  ideally  we  should  always use  one  of  the  two  flashback  parameters. The export  operation  is  performed  with  data  that is  consistent  as  of  the  specified  SCN .  FLASHBACK_SCN and FLASHBACK_TIME are mutually exclusive .

FLASHBACK_TIME : The SCN that most closely matches the specified time is found, and this SCN is used to enable the Flashback utility. The export operation is performed with data that is consistent as of this SCN. TheFLASHBACK_SCN parameter pertains only to the Flashback Query capability of Oracle Database. It is not applicable to Flashback Database, Flashback Drop, or Flashback Data Archive. We can get the scn number from the following query :

SQL> select current_scn from v$database ;       or

SQL>select dbms_flashback.get_system_change_number from dual ; 

Let's have a Demo of the flashback_scn

SQL> select current_scn from v$database;

CURRENT_SCN
------------------------
    1140271

SQL> create table hr.test as select * from test;
Table created.

SQL> select current_scn from v$database;

CURRENT_SCN
-------------------------
    1140487

Let's take a export using flashback_scn  parameter

oracle$ expdp system/ramtech@terminal directory=dpump schemas=hr dumpfile=flashback_hr.dmp logfile=flashlog.log       flashback_scn=1140271

Export: Release 11.1.0.6.0 - Production on Saturday, 16 MAY, 2014 11:35:45
Copyright (c) 2003, 2007, Oracle.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "SYSTEM"."SYS_EXPORT_SCHEMA_01":  system/********@terminal directory=dpump schemas=hr dumpfile=flashback_hr.dmp logfile=flashlog.log    flashback_scn=1140271
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 512 KB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/POST_SCHEMA/PROCACT_SCHEMA
. . exported "HR"."COUNTRIES"                            6.375 KB      25 rows
. . exported "HR"."DEPARTMENTS"                          7.015 KB      27 rows
. . exported "HR"."EMPLOYEES"                            16.80 KB     107 rows
. . exported "HR"."JOBS"                                 6.984 KB      19 rows
. . exported "HR"."JOB_HISTORY"                          7.054 KB      10 rows
. . exported "HR"."LOCATIONS"                            8.273 KB      23 rows
. . exported "HR"."REGIONS"                              5.484 KB       4 rows
ORA-31693: Table data object "HR"."TEST" failed to load/unload and is being skipped due to error:
ORA-02354: error in exporting/importing data
ORA-01466: unable to read data - table definition has changed
Master table "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_SCHEMA_01 is:
  D:\DPUMP\FLASHBACK_HR.DMP
Job "SYSTEM"."SYS_EXPORT_SCHEMA_01" completed with 1 error(s) at 11:37:50

The above error show that the table "test"  is not include in the  export operation because the SCN mention  is of before the table "test" creation. The below export will show the export upto current SCN when database is in use.

Oracle$ expdp system/ramtech@terminal directory=dpump schemas=hr dumpfile=flashback_hr1.dmp  logfile=flashback_log.log  flashback_scn=1140487

Export: Release 11.1.0.6.0 - Production on Saturday, 16 MAY, 2014 11:44:50
Copyright (c) 2003, 2007, Oracle.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "SYSTEM"."SYS_EXPORT_SCHEMA_01":  system/********@terminal directory=dpump schemas=hr dumpfile=flashback_hr1.dmp logfile=flashback_log.log
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 512 KB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/POST_SCHEMA/PROCACT_SCHEMA
. . exported "HR"."COUNTRIES"                                6.375 KB      25 rows
. . exported "HR"."DEPARTMENTS"                          7.015 KB      27 rows
. . exported "HR"."EMPLOYEES"                             16.80 KB     107 rows
. . exported "HR"."JOBS"                                             6.984 KB      19 rows
. . exported "HR"."JOB_HISTORY"                             7.054 KB      10 rows
. . exported "HR"."LOCATIONS"                                8.273 KB      23 rows
. . exported "HR"."REGIONS"                                      5.484 KB       4 rows
. . exported "HR"."TEST"                                              5.054 KB       8 rows
Master table "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_SCHEMA_01 is:
  D:\DPUMP\FLASHBACK_HR1.DMP
Job "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully completed at 11:46:41

Oracle$ impdp system/ramtech@terminal directory=dpump schemas=hr dumpfile=flashback_hr1.dmp  logfile=impflashback_log.log  flashback_scn=1140487

From version 11.2 and higher it is also possible to use the so called legacy mode: you can use the parameters from the old exp utilities! You can use the consistent=y parameter again to make a time consistent export:


$ expdp schemas=scott consistent=y dumpfile=exp_scott.dmp logfile=exp_scott.log directory=DATA_PUMP_DIR

This is the output you will get:
Export: Release 11.2.0.4.0 – Production on Wed Sep 3 15:32:03 2014
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

Username: system
Password:

Connected to: Oracle Database 11g Release 11.2.0.4.0 – 64bit Production
Legacy Mode Active due to the following parameters:
Legacy Mode Parameter: “consistent=TRUE” Location: Command Line, Replaced with: “flashback_time=TO_TIMESTAMP(‘2014-09-03 15:32:03′, ‘YYYY-MM-DD HH24:MI:SS’)”
Legacy Mode has set reuse_dumpfiles=true parameter.
Starting “SYSTEM”.”SYS_EXPORT_SCHEMA_01″: system/******** schemas=RPCR_DEV flashback_time=TO_TIMESTAMP(‘2014-09-03 15:32:03′, ‘YYYY-MM-DD HH24:MI:SS’) dumpfile=rpcr_dev2.dmp logfile=rpcr_dev.log directory=EXP_DIR reuse_dumpfiles=true
Estimate in progress using BLOCKS method…
….

So you see that expdp is translating consistent=y to a flashback_time parameter.

As I said this works only in version 11.2 and higher.