What is the difference between views and materialized views in Oracle?
Views are generally used when data is to be accessed infrequently and data in table get updated on frequent basis. On other hand Materialized Views are used when data is to be accessed frequently and data in table not get updated on frequent basis.
What is the benefit of materialized view?
Benefits of using materialized views Reduce the execution time for complex queries with JOINs and aggregate functions. The more complex the query, the higher the potential for execution-time saving. The most benefit is gained when a query’s computation cost is high and the resulting data set is small.
Can we drop materialized view?
Use the DROP MATERIALIZED VIEW statement to remove an existing materialized view from the database. When you drop a materialized view, Oracle Database does not place it in the recycle bin. Therefore, you cannot subsequently either purge or undrop the materialized view.
Can materialized view be updated?
You can’t insert data into a materialized view as you can with a table. To update the contents of a materialized view, you can execute a query to refresh it. This will re-execute the query used to create it. Executing this refresh query will lock the materialized view so it can’t be accessed while refreshing.
Where are materialized views stored in Oracle?
A materialized view can be stored in the same database as its base tables or in a different database. Materialized views are often used to improve performance, especially when storing data locally that is sourced from tables or views using a database link.
Can materialized view auto refresh?
You can set autorefresh for materialized views using CREATE MATERIALIZED VIEW. You can also use the AUTO REFRESH clause to refresh materialized views automatically.
Can we create materialized view on multiple tables?
– You cannot create a fast refreshable materialized view from multiple tables with simple joins that include an object type column in the SELECT statement.
Can we use join in materialized view?
The following limitations apply to creating materialized views: A materialized view can query only a single table. Joins, including self-joins, are not supported.