Re: Oracle views clarification

Hi,

A "dynamic" view, as you call it, is an access path to the data in one or more tables. Views are sometimes called stored queries because you define a view using a query. The tables referenced in a view's defining query are called the base tables of the view. Once you create a view, you can target the view with standard DML SQL statements such as SELECT, INSERT, UPDATE, and DELETE, just as you would do with a table. However, it is important to understand that views are based on one or more tables -- a view itself does not store data; rather, a view derives its data from its base table(s). Therefore, when you target a view with a SQL statement, Oracle automatically performs the requested operation using the data in the view's base tables. For example, when you query a view, Oracle materializes the view's data at runtime by transforming the query so that it retrieves information from the underlying base table(s).

Unlike a normal view in an Oracle database, a materialized view generates a snapshot of its data and stores the data in one or more data segments. To keep a materialized view's snapshot of data in synch with its underlying base tables, you can schedule the materialized view so that Oracle automatically refreshes its data. When a query targets a materialized view, Oracle reads the pre-computed data from the view's data segment rather than expensively generating the data at runtime. A materialized view is also similar to an index as follows: after you create a materialized view, Oracle can automatically rewrite a query that targets the view's base tables so that the query uses the view and executes more efficiently.

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Hope this helps!
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"Teresa" <tpreto7_at_sapo.pt> wrote in message 
news:6dabc692.0409301805.2e1f407a_at_posting.google.com...


> Hi

>

> Can someone please explain the difference is between an Oracle dynamic

> view & materialized view.

>

> Thank you

> Teresa