Change Data Capture Feature in Oracle Database – Evolution and Benefits
The Change Data Capture feature in the Oracle
database platform is an integrated technology introduced in the 9i version. This
new feature tracked and recorded all modifications in user tables in a
database. These changes were then stored in ETL applications in the changed
tables. The change data was processed and loaded into target data warehouses
and other databases.
The first model of the Oracle CDC technology
worked on triggers set in the source tables that captured any changes as soon
as they were made. However, this method was found to be too invasive by
Database Administrators who were not very willing to work with it.
Shortly thereafter, Oracle released a new form of Oracle
CDC with the 10g version. It was different from the earlier model as the
new one worked by leveraging the redo logs of the source database. This
built-in tool for Oracle CDC was called Oracle Streams. This technology
was a great improvement over the earlier one as it could detect and transfer
change data to a target data storage without adversely affecting the
performance of the database.
This improved technology received a more favorable
response but the company decided to discontinue Oracle Streams after the
release of Oracle 12c leading to the withdrawal of support for Oracle CDC. At
this time, users had no other option but to pay for Oracle GoldenGate for
replication and to get access to this feature.
In thecurrent structure of Oracle CDC, when
the data in one computer changes, another computer has to take some type of
action that is based on that change. The first computer is called the source
database and the second is the target database.
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