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Materialized view [message #5794] Wed, 05 March 2003 15:37 Go to next message
Mark
Messages: 284
Registered: July 1998
Senior Member
Now I am learning about materialized views. As I have realized , they are actually the same as

Create table tab_name
As Select ...
From ...

Am I right or I miss the point ?

What the benefits and disadvantages of materialized views versus Create table As Select ... statement ?

Thanks
Re: Materialized view [message #5795 is a reply to message #5794] Wed, 05 March 2003 17:33 Go to previous message
Todd Barry
Messages: 4819
Registered: August 2001
Senior Member
A materialized view is a copy, a subset, or a summary of a base table. It is then refreshed (either entirely or just with incremental changes) at a specified interval from the base table data.

A table created via CTAS (create table as select) can also be a copy/subset/summary of a base table but there is no automated refresh functionality.

A MV scenario allows you to have a million row base table and then if you update one row, that change is automatically applied to the MV. The whole MV isn't rebuilt (assuming it is not a summarized MV) - which would be very time and resource intensive - just that one row change is propagated.

MV and CTAS - totally different uses.
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