Comments on: difference between materialized views and tables

By: ammalu

ammalu — Fri, 17 Feb 2012 16:31:58 +0000

but we cant do any changes on mv because dml not allowed on mv…………….

By: mohankumar

mohankumar — Tue, 27 Dec 2005 11:29:59 +0000

As the name itself says it gives you all the added advantages of views over table, like selective data sharing. You can build a MV based on many base tables without changing your DB arichiecture using joins.
MV are more usefull for precomputed data store for datawarehouse purposes.

By: pelaez

pelaez — Wed, 21 Dec 2005 12:00:30 +0000

I agree with Mr. Oracle

Query rewrite is a great advantage of MVs.

If you define a materialized view, the optimizer will decide for each query (even those written before the MV) whether using the MV or the underlying tables is the most effective execution plan.

MVs might not be very useful in transactional systems, which get updated all the time, but are handy in business intelligence environments.

By: mroracle

mroracle — Wed, 21 Dec 2005 11:46:08 +0000

The real benefit to MVs is the query rewrite feature… If you have that feature enabled, it will take queries that COULD be using the materialized view instead of what they wrote – and rewrite them BEFORE they get executed!!!

The other advantage as someone else said is the built in mechanisms to keep it updated rather than writing all that yourself.

I hope this helps.

((MrO))

By: cassidy6o6

cassidy6o6 — Wed, 21 Dec 2005 11:37:59 +0000

Hi,

Thanks for your reply. Can I say that the materialized view got the advantage for saving time to write the script to reflash the data as Oracle has written a pl/sql script to handle the refresh. Other than that there is not much difference? If I am willing to write those scripts to update the changes on my table. There is not much difference? Will there be any advantages on materialized views other than tables beside the refreshing?

Cassidy

By: enkidu

enkidu — Wed, 21 Dec 2005 02:52:39 +0000

Hi,

also you do not need any program to refresh the snap-shot tables (mv) There’re built-in pl/sql packages to refresh these types of tables. You can specify a time interval for refresh, even you can define on-commit snap-shots.

regards