Oracle GoldenGate – Initial Load – File to Replicat Method

The File to Replicat Method is similar to the normal CDC (Change Data Capture) method used in the GoldenGate. In this method, the Initial Load Extract extracts the data from the Source Tables and writes it to the Extract File in an Canonical Format. This file is read by the Initial Load Replicat Process and this loads the data using the Database Interface.

One thing should be taken in to considerations. During this Initial Load, you can also enable the Change Synchronization Extract and Datapump processes to record or capture the Online or Incremental changes which happens during the Initial Load and later it can be merged or reconciled with the results of the Initial Load.

File to Replicat is slower when comparing to the Other types/methods of Initial Load because, here the records are applied to the target database one by one. It is applied one record at a time.

ON TARGET

As I mentioned in my earlier postings, For starting the Initial Load, The structure of the tables should be exported from the Source and Imported to the Target database.
This can be done using the EXPDP / IMPDP utility available in the Oracle.

So in this example I have already exported the Schema VEERA from Source and IMPORTED to the Target System (only the structures).

So in Target Table there are no rows inserted. Only the Structure is created.

ON SOURCE

Create the Initial Load Extract Process. 

Configure the Extract process for the Initial Load. The parameters are below,

SOURCEISTABLE – This parameter insists GoldenGate Extract process to extract the data directly from the Source Tables instead from redo logs.

RMTFILE – This is the Extract file on the remote system. The extract process writes the extracted data to this file where then the Replicat process reads these files and applies to the Target system.

Configure the parameters and save the file.

In the ggserr.log file you could see the below.,

To see the Normal or Regular Extract, Datapump or Replicat processes the command is INFO ALL. But in this command the Extract or Replicat processes which are configured for INITIAL LOAD will not be displayed.

To display INITIAL LOAD Processes,

ON TARGET

Create the Initial Replicat Process,

Configure the Replicat process for the Initial Load. The parameters are below,

SPECIALRUN – This parameter tells the Replicat that this is a “ONE-TIME” Process. This is an Initial Load process and not the Normal one. This is process ends with END RUNTIME.

EXTFILE – The Filename present in the Remote system with location. This contains the data which are written by the Extract process for Synchronization of the Target database.

ASSUMETARGETDEFS – This parameter tells the Replicat Process that the Structure of the Source Tables are same as the Target Table.

To view the Parameters,

In the ggserr.log file you could see the below,

ON SOURCE

Now Start the Initial Load Extract Process from the SOURCE SYSTEM,

Wait until the Initial Extraction completes. Once it is finished, start the Initial Load Replicat which is on the Target System.

The below is registered in the ggserr.log,

ON TARGET

Start the Initial Load Replicat and using sqlplus, check if the data are getting loaded to the target table.

As I mentioned before., here the Initial Load Extract extracts the data from the Source Tables and writes it to the Extract File in an Canonical Format. This file is read by the Initial Load Replicat Process and this loads the data using the Database Interface.

We can see the trail file created in the Target system from where the data is loaded to the Target table by the Replicat Process,

In ggserr.log file you could see the below.,

As I mentioned earlier in this post, we should start the Change Synchronization Extract processes before starting the Initial Load Extract process. After the Initial Load is completed, you can start the Change Synchronization Replicat process to apply the Incremental Changes to the Target Database.