What are indexed
views, and does Oracle support them?
As you may already know, a view is a "virtual table". I like to think of a view as a stored SQL statement. A view does not actually contain data, but just a SQL statement to get data from one or more tables.
The performance of a view is tied directly to the performance of the view's underlying SQL statement. Some systems will let you create an index on the view so that selecting data from the view will be faster. Oracle databases do not support indexing views.
But Oracle does support a Materialized View (MV). A MV is like a view, but it does contain data. MV's are primarly used for preaggregating results to speed up performance. And you can place an index here.
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This was first published in September 2002