Dependent materialized views can be refreshed during online table redefinition only if the materialized view is fast refreshable and is not a ROWID-based materialized view or materialized join view. Materialized views that do not follow these restrictions are not refreshed. CREATE MATERIALIZED VIEW fast _ rf_union _all_mv AS SELECT x. AS marker FROM p, r WHERE p. This can be specified as long as the materialized view is fast refreshable (in other words, not complex).
The ON COMMIT privilege is necessary to use this mode. This usually means more than one table or using functions in the SQL clause. Because the materialized view conforms to the conditions for fast refresh , the database will perform a fast refresh. The following statement creates the oe.
FAST _ REFRESHABLE : VARCHAR2(18) Indicates whether the materialized view is eligible for incremental ( fast ) refresh. Hello Masters :-), I read the documentation about fast refreshable materialized views. It states: The changes for conventional DML changes are stored in the materialized view log associated with the master table.
Find Great Deals Now! Check Out Top Brands On eBay. The frequency of this refresh can be configured to run on-demand or at regular time intervals. In practice, many Oracle customers use materialized views.
The key checks for FAST REFRESH includes the following: 1) An Oracle materialized view log must be present for each base table. The RowIDs of all the base tables must appear in the SELECT list of the MVIEW query definition. If there are outer joins, unique constraints must be placed on the join columns of the inner table.
Also, unique constraints must exist on the join columns of the inner join table. Fast refreshable materialized view errors, part six: MV_CAPABILITIES_TABLE. This post summarizes the previous posts by reversing the angle. The complication comes from the lag between the last refresh of the materialized view and subsequent DML changes to the base tables. Some materialized views have status invali however, they compile with no errors.
Both the sources databases are in Oracle. My Oracle version is 11. We have got new business requirement that we have to now refresh our MVs with FAST method during business hours.
We initially thought to create MVs with FAST refresh on COMMIT.
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. After creating the required materialized view logs (based on the Oracle 9i documentation FAST REFRESH requirements) the DBMS_MVIEW. Oracle Database - Enterprise Edition - Version 10.
MV_CAPABILITIES_TABLE proved to be invaluable and less than 1hours of analysis and unit testing resulted in refactoring the materialized views for FAST REFRESH dramatically reducing the refresh time from more than hours to less than making the Discoverer Plus reports available to the business analysts and management by 8am. The materialized view must not contain references to RAW or LONG RAW data types. It cannot contain a SELECT list subquery.
The SELECT list of each query must include a UNION ALL marker, and the UNION ALL column must have a distinct constant numeric or string value in each UNION ALL branch. To fast refresh a materialized join view , you must create a materialized view log for each of the tables referenced by the materialized views. Creating a fast refreshable MVIEW with max function on select causes the fast refreshable limitation to DIRLOAD_LIMITEDDML. However, even with an empty materialized view log on the source table, the materialized view keeps COMPLETE refreshing.
With the fast refresh Oracle keeps track of the changes for the base tables and applies the changes to the materialized view when it is refreshed. A complete refresh on the other hand rebuilds the materialized view from scratch.
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