materialized views

What are CBO and RBO?

In large applications that juggle tons of data, it isn’t enough to get a query to run without errors. The query must also perform well — get the results in fastest possible time, using the least possible resources.

This is where Oracle’s inbuilt optimizers come into play. Till Oracle 9i, Oracle server provided the options of CBO (cost-based optimizer) and RBO (rule-based optimizer). RBO has been desupported by Oracle 10G onwards, but it is still worth knowing about to understand the evolution of Oracle’s optimization techniques.

This post explores the key differences between CBO and RBO.

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The Difference Between Views and Materialized Views

Other than the word "view" in their names and the fact that both are defined by an underlying SQL, there is little else common between Oracle views and materialized views – yet they can be a source of great confusion if you are new to these database objects.

Here’s a summary of the key differences between views and materialized views, to put an end to all mix-ups. By the end of the article, you should be in a position to decide if your specific scenario needs a view, a materialized view, or neither.

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