Oracle Change Data Capture: Concept, Benefits, Modes

  

Oracle CDC helps real-time data integration across enterprises, speeds data warehousing, and improves the performance and availability of databases. It also enables several replication tasks without lowering the performance of the source database.

Among the tasks that may be carried out with Oracle CDC are offloading analytics queries from databases in production to data warehouses or other analytical platforms. It is also possible to migrate databases to the cloud without downtime and extract incremental data from multiple sources for transfer to a data warehouse.


Benefits of Oracle CDC

There are several benefits of Oracle Change Data Capture.

  • Oracle CDC records all operations like Insert, Update, and Delete along with all values before and after the modifications.
  • Asynchronous CDC can be configured to have a negligible impact on the source database.
  • CDC includes DBMS_CDC_PUBLISH and DBMS_CDC_SUBSCRIBE packages, which help to easily publish and subscribe to interfaces.
  • Running costs of databases are reduced with Oracle CDC, as the extraction of modified data from the Oracle database is greatly simplified.  

Capturing and Publishing Change Data Capture

There are two modes to capture changed data with Oracle CDC.

  1.    Synchronous: Triggers are set at the source database, ensuring that changed data is    captured immediately. This is because each SQL statement performs a DML (Data    Manipulation Language) activity (Insert, Update, or Delete). In this mode,   modified data is captured as a part of the transaction that changes the source table.
  2.    Asynchronous: In this mode, data is sent to the redo log files, and changed data is   captured only after a SQL statement performs a DML activity. Modified data is not   captured as a component of the transaction that changes the source table and therefore   has no effect on that transaction. The three modes of asynchronous CDC are HotLog,   Distributed HotLog, and AutoLog. 

Comments

Post a Comment

Popular posts from this blog

SQL Server Change Data Capture – A Comprehensive Overview

Image
  Microsoft launched its SQL Server CDC product in 2005 with several cutting-edge and technologically advanced features, such as “after update”, “after insert”, and “after delete” abilities. Since this technology was very complex and not received well by DBAs, Microsoft released a revised and more advanced version of the SQL Server CDC in 2008, which became very popular and is still in use today. The Concept of SQL Server Change Data Capture SQL Server CDC captures and records changes made in the source database, such as “Insert”, “Update”, or “Delete”. These can be accessed by any user seamlessly, with all details available in an easy-to-understand relational format. CDC provides all the information required for capturing the changes to an intended target. The data for modified and changed rows is available in CDC. The changes made are stored in tables and are reflected in the structure of the tracked source tables. For data security, access to the table-valued functions of ...
Read more

What is SQL Server Change Data Capture – Evolution and Function

Image
  The goal of SQL Server CDC is to capture any changes made in a source database and present them to users in a simple relational format. Types of changes include insert, update, and delete to the database. All inputs required to capture these changes to the target, such as column information and metadata, are available for the modified and changed rows. After the changes are made and noted in the tables at source, they are replicated in the column information of the target tables. As a matter of database safety and security, access to the changes is monitored closely. Development of SQL Server CDC It was in 2005 that Microsoft launched SQL Server CDC with “after update”, “after insert”, and “after delete” features. However, DBAs found its working quite complex. Based on this feedback, Microsoft introduced a revised version in 2008, which was very user-friendly, well-received, and is still in use today. In this version, database administrators can capture and store changes ma...
Read more

An Overview Of Moving Databases From Oracle to SQL Server

Image
  Let us start with why you should migrate databases from Oracle to SQL Server.  Benefits of Oracle to SQL Server database migration   Most important is the cost factor since using Oracle can be very expensive, especially if all the features like Oracle Enterprise Manager or Oracle Data Guard are used. SQL Server, on the other hand, offers all advanced database engine features like Analysis Services or Reporting Services in one license cost.  The SQL Server can better handle large volumes of data processing loads.  Oracle users get locked into a single vendor with high licensing costs. However, Microsoft SQL Server offers several versions, with users having the flexibility to choose one as per the features required and pay accordingly. Among the versions are the Enterprise and the Standard models.  SQL Server keeps costs down through merging databases, visualizing servers, allotting resources optimally, and compressing data. This leads to more streamli...
Read more