Step 2 - Replication Pairs

Owned by Arjen Visser
Last updated: Apr 21, 2014 by Chris Lawless (Deactivated)
3 min read

The following settings are available in "Step 2 - Replication pairs" of the setup wizard.

Select source database: 

Specify the source database for the replication. This is the database where the data will be replicated FROM.

Select target database:

Specify the target database for the replication. This is the database where the data will be replicated TO.

Will be DDL replication enabled? (If YES, the script will grant more privileges to the Dbvisit Replicate users and enable database-wide supplemental logging)

Specify if DDL replication is enabled. When DDL replication is enabled, then any structural changes to the table will also be replicated such as DROP COLUMN, ADD COLUMN, DROP TABLE etc. This does not include storgage or partition changes. 

Use fetcher to offload the mining to a different server? (yes/no)

Specify if the fetcher process should be enabled to offload the MINE process to another server. See Dbvisit Replicate FETCHER Process for more information.

Would you like to encrypt the data across the network (yes or no) 

Specify if you would like to encrypt the data as it moves across the network.

Would you like to compress the data across the network (yes or no) 

Specify if you would like to compress the data as it moves across the network.

How long do you want to set the network timeouts. Recommended range between 60-300 seconds [60]

Specify the number of seconds you would like to set if the network has a timeout.

Lock and copy the data initially one-by-one or at a single SCN? (one-by-one/single-scn/ddl-only/resetlogs)

Defines how the tables will instantiated. This specifies which SCN to use to define the starting point. The options are:

  • one-by-one : This obtains a unique SCN for each table to replicate from. No locks are required on the tables.
  • single-scn : This locks the tables and obtains a single SCN for all tables to replicate from. Locks are required on the tables. See Single SCN Prepare for more information.
  • ddl_only : This does not obtain an SCN to replicate from. This is used when there is no initial data to be copied before the replication starts. The target tables will be empty before replication starts.
  • resetlogs : This is used when a complete copy of the source database is made (for example with RMAN) and restored as a target database. When the target database is opened with a resetlogs command, then the SCN is used from the last resetlogs at the target database. It obtains the value from v$database.resetlogs at the target database. 

For more information see Creating the Starting Point (data instantiation)

What data copy script to create? (dp_networklink/dp_exp/exp/ddl_file/ddl_run/none)

Defines how the initial data copy is created at the target database before replication starts. Depending on the version of Oracle, datapump or exp/imp scripts will be created. The script unloads (exports) the data from the source database and loads (imports) it directly into the target database.

The script that is created is called APPLY.sh or APPLY.bat (if ddl_file is chosen, the file is called APPLY.sql). This script is not created during the setup wizard. It will be created during the setup and initialization of the replication when the *-all.sh or *-all.bat script is run. 

The options are:

  • dp_networklink : This creates a datapump script which uses a network link connection between the source and target database. A DATABASE link needs to exist between source and target databases. The script can be run and this uses the database link to copy and load the data from the source database into the target database. 

  • dp_exp : This creates a datapump script containing export and import commands for the replicated tables. An example of this is:

    echo ========================================
echo EXPORT
echo ========================================
expdp SYSTEM/oracle@orcl dumpfile=AVI_SALES.dmp directory=DATA_PUMP_DIR flashback_scn=56898473 tables=AVI.SALES logfile=exp_AVI_SALES.log
echo ========================================
echo IMPORT
echo ========================================
impdp SYSTEM/oracle@test11202 dumpfile=AVI_SALES.dmp directory=DATA_PUMP_DIR logfile=imp_AVI_SALES.log

    The dumpfile is extracted out of the source database and imported into the target database using the TNS connection strings specified during the replication configuration. Enough space will be required on the filesystem to hold the .dmp file. 

  • exp : This creates an exp/imp script containing export and import commands for the replicated tables. The export is extracted out of the source database and imported into the target database using the TNS connection strings specified during the replication configuration. Enough space will be required on the filesystem to hold the .dmp file. 
  • ddl_file : This creates the DDL script (APPLY.sql) to create the table(s) in the target database. No data will be copied only the table definitions. This is useful when the CDC/Audit/BI options is chosen to create the target staging tables. 
  • ddl_run : This creates the table(s) in the target database directly by Dbvisit Replicate. No data will be copied only the table definitions. This is useful when the CDC/Audit/BI options is chosen to create the target staging tables. 
  • none : No script or action is taken. 

For more information see Using Data Pump (and exp/imp)