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What is Data instantiation

Before data replication can start, the target database must have a copy of the database objects that are going to be replicated. It is also necessary that the data for the objects to be replicated are completely in sync at the point at which the replication starts. This is done with the Oracle SCN. By using the Oracle SCN it is guaranteed that no transactions are lost during the replication setup. 

The Oracle SCN is captured to enable to pick a snapshot of the data at a point in time. This Oracle SCN is then used in two ways:

  1. Everything before the SCN must be copied manually. This is called Data Instantiation and is done in this example through Oracle DataPump.
  2. Everything after the SCN is replicated by the replication tool (in this case Dbvisit Replicate)

Running DataPump

1. On the target server (dbv02), ensure that the OE schema is clean. Run the following script to ensure that there are no OE objects. If there are then the DataPump script will fail.

sqlplus oe/oe@ttorcl_trg
SQL> @/u01/oracle/swingbench/sql/soedgdrop2.sql
SQL> exit

2. On the target server (dbv02), setup the database link as user system.

sqlplus system/oracle@ttorcl_trg
SQL> CREATE public DATABASE LINK ttorcl_src CONNECT TO system IDENTIFIED BY oracle USING 'ttorcl_src';
SQL> exit

This database link is needed for the Datapump script that is created as APPLY.sh. The content of datapump script APPLY.sh is similar to:

impdp SYSTEM/oracle@ttorcl_trg table_exists_action=TRUNCATE network_link=ttorcl_src directory=ttorcl_trg_DATA_PUMP_DIR flashback_scn=3144204 tables=OE.ADDRESSES,OE.CARD_DETAILS,OE.CMP3$95780,OE.CMP4$95780,OE.CUSTOMERS,OE.INVENTORIES,OE.LOGON,OE.ORDERENTRY_METADATA,OE.ORDERS,OE.ORDER_ITEMS,OE.PRODUCT_DESCRIPTIONS,OE.PRODUCT_INFORMATION,OE.PROMOTIONS,OE.WAREHOUSES   logfile=OE_WAREHOUSES.log JOB_NAME=DP_dbvrep_orcl_0001

The flashback_scn number (in this case 3144204) determines the consistency point as to where the data will be loaded to. All data prior to this SCN will be loaded using the above DataPump script. All data past this SCN will be replicated using Dbvisit Replicate.

3. On the source server (dbv01) start the APPLY.sh script. This script will take approximately 25 minutes to complete.

$ ./APPLY.sh 
Import: Release 12.1.0.1.0 - Production on Fri Aug 1 05:25:47 2014
Copyright (c) 1982, 2013, Oracle and/or its affiliates.  All rights reserved.
Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
Starting "SYSTEM"."DP_DBVREP_ORCL_0001":  SYSTEM/********@ttorcl_trg table_exists_action=TRUNCATE network_link=ttorcl_src directory=DATA_PUMP_DIR flashback_scn=14491671 tables=OE.ADDRESSES,OE.CARD_DETAILS,OE.CUSTOMERS,OE.INVENTORIES,OE.LOGON,OE.ORDERENTRY_METADATA,OE.ORDERS,OE.ORDER_ITEMS,OE.PRODUCT_DESCRIPTIONS,OE.PRODUCT_INFORMATION,OE.WAREHOUSES logfile=OE_WAREHOUSES.log JOB_NAME=DP_dbvrep_orcl_0001 
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 1.008 GB
Processing object type TABLE_EXPORT/TABLE/TABLE
. . imported "OE"."ORDER_ITEMS"                         4290023 rows
. . imported "OE"."INVENTORIES"                          900632 rows
. . imported "OE"."ORDERS"                              1429790 rows
. . imported "OE"."ADDRESSES"                           1500000 rows
. . imported "OE"."CUSTOMERS"                           1000000 rows
. . imported "OE"."CARD_DETAILS"                        1500000 rows
. . imported "OE"."LOGON"                               2382984 rows
. . imported "OE"."PRODUCT_DESCRIPTIONS"                   1000 rows
. . imported "OE"."PRODUCT_INFORMATION"                    1000 rows
. . imported "OE"."ORDERENTRY_METADATA"                       4 rows
. . imported "OE"."WAREHOUSES"                             1000 rows
Processing object type TABLE_EXPORT/TABLE/GRANT/OWNER_GRANT/OBJECT_GRANT
Processing object type TABLE_EXPORT/TABLE/INDEX/INDEX
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type TABLE_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type TABLE_EXPORT/TABLE/INDEX/FUNCTIONAL_AND_BITMAP/INDEX
Processing object type TABLE_EXPORT/TABLE/INDEX/STATISTICS/FUNCTIONAL_AND_BITMAP/INDEX_STATISTICS
Job "SYSTEM"."DP_DBVREP_ORCL_0001" successfully completed at 20:20:50
[oracle@source dbvrep_orcl]$

During the import of the data, the archiver will become stuck because there will not be enough space.

Run the following script a few times on the target server (dbv02) to ensure that the flash recovery area does not fill up and pause the import:

/usr/local/bin/del_arch.sh orcl 0
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