#oracle cdc

Oracle Change Data Capture (CDC) is a technology that is widely used today for multiple activities that are critical in today’s organizations. CDC is optimized for detecting and capturing insertions, updates, and deletions that are applied to tables in an Oracle database. The technology is also an essential feature of any Oracle replication solution as CDC classifies and records changed data in a relational format that is suitable for use in EAI, ETL, and other applications.

Businesses using Oracle databases from Oracle CDC have several advantages. Data warehousing costs are lower and real-time data integration done by extracting and loading data into data warehouses and other data repositories incrementally and in real-time are allowed. When only the data that has changed after the last extraction is transferred, Oracle CDC does away with the need for bulk data updating, batch windows, and complete data refreshes that can disrupt users and businesses.

Development of Log-Based Oracle CDC

The Oracle 9i version of Oracle was released in 2001 with a new feature. Users of the database had access to a built-in mechanism for tracking and storing changes in real-time as they happened – a native Oracle CDC feature. However, database administrators faced a major disadvantage as it depended on placing triggers on tables in the source database, thereby increasing processing overheads.

This feature was fine-tuned in the Oracle 10g model. A new Oracle CDC technology was introduced that used the redo logs of a database to capture and transmit data without using the previous invasive database triggers. An Oracle replication tool called Oracle Streams was used for this activity.

This new version of Oracle CDC was primarily log-based form of change data capture that was lightweight and did not need the structure of the source table to be changed. Even though this latest model of CDC became quite popular, Oracle decided to withdraw support to Oracle CDC with the release of Oracle 12c. Users were encouraged to switch to the higher-priced Oracle Golden Gate, an Oracle replication software solution.  

Oracle CDC Modes

The Oracle Data Integrator supports two journalizing modes.

The first is the Synchronous Mode. Here triggers are placed in tables in the source database and all changed data at source is immediately captured. Each SQL statement in the table completes a Data Manipulation Language (DML) activity which is insert, update, or delete. The changed data is captured as an integral component of the transaction which changed the data at the source. This mode of Oracle CDC is available in the Oracle Standard and the Oracle Enterprise Editions.

Before going to Oracle Change Data Capture (CDC), it is necessary to understand the concept of CDC. Change Data Capture (CDC) is software design patterns that are mainly used to monitor changes in data in the source database. This is done so that at a later stage, relevant action can be taken on the changes made. Data capture, data identification, and data delivery are all integral components of CDC.

Now coming to Oracle CDC, this technology assists real-time data integration across system networks of enterprises thereby speeding up data warehousing activities and improving manifold the performance and availability of databases. A critical benefit of Oracle CDC is that when replication is done on Oracle database with technologically advanced tools and non-intrusive methods, there is no performance degradation or lag in speeds. These tasks include offloading analytics queries from databases in production to data warehouses and migrating databases to the cloud without stopping work or downtime. Changes made to data, also called incremental data for additions to the databases, can be extracted from different sources and transferred to a data warehouse with Oracle CDC.

One of the main functions of Oracle Change Data Capture is preserving and capturing the state of the data. It can either be in any database or in a data warehouse environment that can also be used in a data repository system. Hence, the task of developers for setting up Oracle CDC mechanisms is made easy as they can avail multiple ways to do so, starting from application logic to physical storage in one or several groupings of system layers.

Modes of Oracle CDC

Oracle Data Integrator supports two journalizing modes.

·        Synchronous Mode: Triggers are placed at the source database. This makes sure that all changes to the data are triggered and captured immediately. Thus, each SQL statement executes a Data Manipulation Language (DML) activity which is inserting, deleting, or updating data. In Synchronous mode, the changed data is taken as a part of the transaction that changed the data at source. This feature of Oracle CDC is included in the Oracle Standard Edition and the Oracle Enterprise Edition.

·        Asynchronous Mode: Data is sent to the redo logs. The changed data is captured after SQL statement is executed through a DML process. Here, the changed data is not captured as a part of the transactions that were responsible for changes to the table at source and therefore, do not affect the transaction. The three modes of asynchronous Oracle CDC are Auto Log, Hot Log, and Distributed Hot Log. The Asynchronous Change Data Capture is based on and offers a relational interface to the now discontinued Oracle Streams.  

Oracle database management system has been optimizing business efficiencies of organizations around the world since it was commercially launched in 1991. This is especially true for enterprises that operate in a fully data-driven environment.

Oracle is the ideal base for running data warehouses, intricate queries, and transaction processing and is known for its open-source platform and technologically advanced features. These include advanced data analysis functionalities, a robust querying layer, access controls, optimized support structure, and most critically, ACID-compliant enterprise-grade security. The combination of a distinct data warehouse and the traditional database has made this database management platform a very popular ETL stack.

Oracle CDC (Change Data Capture)is the technology where real-time data integration across enterprises is improved through the availability and performance of databases by speeding up data warehousing solutions. Many replication processes are done with Oracle CDC without users facing any lag or performance degradation more so when the replication activities are carried out with cutting-edge tools and efficient and non-intrusive methods.

These tasks include offloading analytics queries from databases in production to analytical platforms and data warehouses and migrating databases to the cloud without any downtime or system stoppages. Incremental data can also be extracted from multiple sources through Oracle CDC before being transferred to a data warehouse.

Change Data Capture is an optimized and highly effective solution for reducing data warehousing costs. It is because Oracle CDC extracts and loads data into data storage repositories and any data warehouse incrementally and in real-time. Since the changes that are made only to the database at the source are recorded, organizations need not carry out time-consuming full refreshes to the database every time a change is made at the source.

Change Data Capture is based on the concept that whenever the data stored in one computer or system is changed, another computer has to take some action based on those changes. The first is called the source system and the second the target database. It is quite possible that the source and the target systems are the same and, in this case, too Oracle CDC is very effective.    

CDC explained simply is software design patterns that are used to track changes in the input database so that action taken on the changes made can be done at a later date. It is also the process where data identification, data capture, and data delivery are implemented through data integration for all changes made to the source database.

Oracle CDC optimizes capture and detection of mentions, deletions, and any updates applied to any tables in an Oracle database. This technology is a very important component of Oracle database replication where CDC classifies and records changes made to data in a relational format that is ideal for being used in EAI, ETL, or other applications.