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Oracle CDC PowerPoint Presentation

Oracle CDC

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Oracle CDC

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  1. How Does Changed Data Capture in Oracle Databases Work

  2. Before going into the intricacies of Changed Data Capture (CDC) on Oracle databases, it will be relevant to understand more about what is CDC.  In any business, inserts, updates, and deletes are continually made in databases and it has to be ensured that the history of all such changes is scrupulously recorded and maintained. This is what CDC is all about and is the process where changes made at the source database are captured and applied throughout the organization. The objective of the CDC, regardless of whether it isOracle CDCor Microsoft SQL Server CDC is to ensure that data is effectively synchronized by minimizing the requirements for the ETL process (Extract, Transform, and Load).

  3. All deletions, insertions, and updating of activities to any table are recorded by Changed Data Capture and are available in a user-friendly relational format. Metadata and column information that are required to apply the changes to a target source is captured for the changed rows and stored in specific change tables. These give details of the column structure of the tracked source tables. Therefore, CDC provides table-valued functions that permit access to changed data. Coming now to Oracle CDC,how to use the CDC feature in Oracle Data Integrator to track changes to the data and process these changes in the integration flows.  Oracle CDChelps the Oracle Data Integrator to track changes in source data from other applications. This is possible because the Data Integrator can bypass processing unchanged data in the flow when integration interfaces are run.   

  4. There are multiple benefits of limiting the source data flow to changed data only, primarily in cases of data synchronization and replication. These are critical for setting up an event-oriented architecture for integration where data changes are made during a business process by applications. Oracle CDCthrough the Oracle Data Integrator transforms the changes into events that are then circulated throughout the databases and information systems.  Oracle CDCis done by journalizing models and setting up an infrastructure to capture the changes made to the records of the existing databases.  Two journalizing modes are supported by the Oracle Data Integrator.  The first is the Simple Journalizing model which tracks all changes in the individual data stores in a model. The second is the Consistent Set Journalizing. This model tracks changes to a group’s data stores and considers mainly the referential integrity between the data stores. In this mode, it is the Consistent Set group of data stores that is journalized.  Setting up the basic process of Oracle CDC on an Oracle Data Integrator model is not a long-drawn or complex affair and can be completed in five stages. These are setting the CDC parameters in the data model, adding the data stores to the CDC, setting the order of the data stores to ensure consistent set journalizing, adding subscribers, and finally, starting the journals.