There are many reasons why Oracle has been a mainstay of businesses for decades. It is designed to work with data warehouses, complex queries, transaction processing and more. It also offers enterprise-class security, a robust query layer, advanced data analysis capabilities, access control, and maximum support. Enterprise use of distributed storage systems with open source code has made the merging of the traditional Oracle transactional database and a separate data warehouse a very popular ETL stack.
One of the most important features of Oracle is Oracle Change Data Capture, which captures all changes such as commits, updates or deletes applied to an Oracle database. This technology is integrated with Oracle’s replication capability, with the DDC marking changes and labeling data in a relational format suitable for ETL, EAI and other applications.
Oracle Change Data is a cost-effective option for companies using Oracle Database. This reduces storage costs because DCC retrieves and transfers data or other storage media incrementally in real time. Only changes are taken into account and there is no need to update extensive data or the entire database every time a change is made to the source. This results in considerable savings in time and money.
Developing Oracle Change Data Capture
Although Oracle was launched in 1979, it wasn’t until 2001 that Oracle 9i was released with Oracle Change Data Capture. This model relied on placing triggers on the original database tables, a process that was considered too complicated and time consuming by DBAs. However, Oracle has made progress with the 10g version. The entire technology has undergone a complete overhaul, now using redesigned database protocols for the CDC. When combined with Oracle Streams, Oracle’s replication tool, data changes can be captured and transferred without using database triggers.
At the time, Oracle Change Data Capture was essentially a log-based DDC model. This means that the structure of the source table was not allowed to change during the implementation of the CDC. But although this CDC mode became very popular, Oracle stopped supporting it after the release of Oracle 12c. At the time, users had no choice but to switch to Oracle GoldenGate, Oracle’s expensive replication software.
How does Oracle Change Data Capture work?
First, the required logging templates and infrastructure must be configured before Oracle CDC runs. Allows you to capture and save changes to existing databases. Oracle Data Integrator supports two logging modes. One is a simple logging model that records all changes in a separate data repository. The other is the sequential journalism model. This mode identifies changes to the group’s data warehouse, ensuring the referential integrity of the data warehouses. Only the datastore group of the coherent set is recorded.
Oracle changeoverData collection types
There are two types of Oracle CDC, and companies should choose the type that meets their specific needs.
- Synchronous change of data acquisition : With this type of DCC, triggers are inserted into the data in the change table as soon as the existing data is changed. So as soon as changes are detected, these points are activated. In this process, a user is created who acts as the editor for the change data. This user must have access to the source and namespace tables from which all changes made are tracked and recorded.
The next step is to create the changeset and the tables that will subscribe to the changed data. However, before performing this operation, i.e. copying the changes to the target database, a script must be developed that is capable of pasting the data into the target database. The disadvantage of this synchronous data collection is that the triggers affect the performance of the original database.
- Asynchronous input of change data : The disadvantage of synchronous DDC has been solved by Oracle in this procedure. Here the data of all database activities are stored in newly designed logs. The advantage is that the entire CDC process is performed without affecting the speed and performance of the Oracle database.
Both methods are useful and organizations are entirely free to choose which one they use.
Configuring data collection when switching to the Oracle operating system
The Oracle CDC configuration comes with its own set of tasks. Initialization and completion require several changes to user rights and configuration. In addition, Oracle CDC is based on recording and capturing change data. Therefore, developers need to implement logic to process the data and enter it into the target database.
Entering Oracle change data is not a complicated process if you use the right methods and tools.
frequently asked questions
What is data entry for changes in Oracle?
Change Data Capture efficiently identifies and captures data that has been added, updated, or deleted in Oracle relational tables and makes the changed data available for use by applications. Change Data Capture is deployed as a server side component of Oracle Database with Oracle9i.
How is data collection evolving?
Change Data Capture (CDC) identifies and captures only the most recent changes to production data and metadata captured by the source within a specified time period, usually measured in seconds or minutes, and then allows data replication software to copy those changes to a separate data store.
What is data collection in ETL?
Change Data Capture (CDC) is a process that captures changes to a database and ensures that these changes can be replicated at a target, such as a data warehouse.
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