Answer Posted / satya

Materialized views are schema objects that can be used to
summarize, precompute, replicate, and distribute data. E.g.
to construct a data warehouse.

A materialized view provides indirect access to table data
by storing the results of a query in a separate schema
object. Unlike an ordinary view, which does not take up any
storage space or contain any data.

The existence of a materialized view is transparent to SQL,
but when used for query rewrites will improve the
performance of SQL execution. An updatable materialized view
lets you insert, update, and delete.

You can define a materialized view on a base table,
partitioned table or view and you can define indexes on a
materialized view.

A materialized view can be stored in the same database as
its base table(s) or in a different database.
Materialized views stored in the same database as their base
tables can improve query performance through query rewrites.
Query rewrites are particularly useful in a data warehouse
environment.

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