Updating a materialized view in oracle
Unlike indexes, materialized views can be accessed directly using a statement.
However, it is recommended that you try to avoid writing SQL statements that directly reference the materialized view, because then it is difficult to change them without affecting the application.
The introduction of summary management eased the workload of the database administrator and meant the user no longer needed to be aware of the summaries that had been defined.
The database administrator creates one or more materialized views, which are the equivalent of a summary.
Instead, let query rewrite transparently rewrite your query to use the materialized view.
Note that the techniques shown in this chapter illustrate how to use materialized views in data warehouses.
Data warehouses commonly range in size from tens of gigabytes to a few terabytes.
Usually, the vast majority of the data is stored in a few very large fact tables.
Queries go directly to the materialized view and not to the underlying detail tables.The end user queries the tables and views at the detail data level.The query rewrite mechanism in the Oracle server automatically rewrites the SQL query to use the summary tables.A materialized view definition can include any number of aggregations ( package to help in designing and evaluating materialized views for query rewrite.If a materialized view is to be used by query rewrite, it must be stored in the same database as the detail tables on which it relies.
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They can also be used to precompute joins with or without aggregations.