Well, we can query the DBA_MVIEW_ANALYSIS. If a materialized view contains many rows and the base table's rows change infrequently refreshing the materialized view completely can be an expensive operation. In earlier releases the parameter was set to FALSE by default but now it is set to TRUE, which forces a DELETE of the materialized view instead of TRUNCATE, making the materialized view more "available" at refresh time. To do so, let’s call SQL query given below: REFRESH MATERIALIZED VIEW … The materialized view fast refresh mechanism is a one-size-fits-all solution, and is probably not efficient for 99% of summary table maintenance operations. To execute this command you must be the owner of the materialized view. In order to disable that you must break the dbms_job that was created in order to refresh the view. We will explore this type of refresh next. IMMEDIATE REFRESH statement. I did 'alter materialized view mv_nm refresh start with sysdate+0.1/24 next sysdate+1/24', and checked dba_jobs - the job was scheduled to run in 0.1 hour, but after an hour, I checked the NEXT column in dba_jobs, it's still the original one, I checked dba_mview, the last_refresh was still a few days ago - it did not refresh. Description. A materialized view stores data in two places, a clustered columnstore index for the initial data at the view creation time, and a delta store for the incremental data changes. Make a Refresh Group: ADD: Add materialized view to the refresh group: SUBTRACT: Remove materialized view from the refresh group: REFRESH: Manually refresh the group: CHANGE: Change refresh interval of the refresh group: DESTROY: Remove all materialized views from the refresh group and delete the refresh group Usually, a fast refresh takes less time than a complete refresh. The expression is evaluated at the conclusion of each refresh so you just need to ensure that the expression evaluates to whatever time you want at that particular instant in time. Which materialized view in a group is being refreshed? We see real time data in a VIEW. will specify that the refresh happens every day at 2 AM. CREATE MATERIALIZED VIEW: specify what’s being created. Description. Just like we saw with our regular view, materialized views begin the same way, by executing a command to generate a new view migration: rails g scenic:view mat_top_scorers. Creates a materialized view (also called a snapshot), which is the result of a query run against one or more tables or views. But this DELETE is an expensive operation in terms of refresh time it takes. ALTER MATERIALIZED VIEW changes various auxiliary properties of an existing materialized view.. You must own the materialized view to use ALTER MATERIALIZED VIEW.To change a materialized view's schema, you must also have CREATE privilege on the new schema. A materialized view log (snapshot log) is a schema object that records changes to a master table's data so that a materialized view defined on that master table can be refreshed incrementally. Greg Clough Senior Oracle DBA. Is the refresh hanging or moving slowly? The system does not allow an insert, update, or delete on a view. If WITH DATA is specified (or defaults) the backing query is executed to provide the new data, and the materialized view is left in a scannable state. I’ve created a view. Therefore, whenever a transaction commits which has updated the tables on which a materialized view is defined, those changes are automatically reflected in the materialized view. Creating a materialized view. The old contents are discarded. 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