Materialized view [message #5794] |
Wed, 05 March 2003 15:37 |
Mark
Messages: 284 Registered: July 1998
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Senior Member |
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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
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Re: Materialized view [message #5795 is a reply to message #5794] |
Wed, 05 March 2003 17:33 |
Todd Barry
Messages: 4819 Registered: August 2001
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Senior Member |
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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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