Incremental update for data warehouse analysis!
For incremental update the popular strategy is trigger and mining log.
The materialized view and synchronous CDC is replicating data utilizing the trigger strategy.
Stream and asynchronous utilizing the mining log.
CDC(Change Data Capture) is designed for the incremental extract for ETL which can be divided by Asynchronous and synchronous. We need not synchronous. So let us analyze the asynchronous. CDC also provide the interface to stream.
Oracle Streams enables information sharing. Using Oracle Streams, each unit of shared
information is called a message, and you can share these messages in a stream. The
stream can propagate information within a database or from one database to another.
The stream routes specified information to specified destinations. The result is a
feature that provides greater functionality and flexibility than traditional solutions for
capturing and managing messages, and sharing the messages with other databases
and applications. Streams provides the capabilities needed to build and operate
distributed enterprises and applications, data warehouses, and high availability
solutions.
We can use stream for data warehouse loading.Data warehouse loading is a special case of data replication. Some of the most criticaltasks in creating and maintaining a data warehouse include refreshing existing data,and adding new data from the operational databases. Streams components can capture
changes made to a production system and send those changes to a staging database or
directly to a data warehouse or operational data store. Streams capture of redo data
avoids unnecessary overhead on the production systems. Support for data
transformations and user-defined apply procedures enables the necessary flexibility to
reformat data or update warehouse-specific data fields as data is loaded. In addition,
Change Data Capture uses some of the components of Streams to identify data that
has changed so that this data can be loaded into a data warehouse.
The difference between the CDC and stream.
CDC encapsulate the complex details for replication so it is simpler than stream.
Stream give you more option to meet you needs and provide the interface for user definition procedures.