Materialized views are a really useful performance feature, allowing you to pre-calcuate joins and aggregations, which can make applications and reports feel more responsive. regards. Materialized Views are often used in data warehouses to improve query performance on aggregated data. your help will be appreciated. We only had DML on the base tables. Why it is so and how to fix it? We got ora-4045 while running a query again a materialized view. Have also a look at Invalidating Materialized Views in the Database Data Warehousing Guide and the ALL_MVIEWS Reference in the documentation. The solution was to re-create the Log, then perform a … A materialized view log is a schema object that records changes to a base table so that a materialized view defined on the base table can be refreshed incrementally. 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. Here are some basic rules to improve refresh performance.Unlike indexes, materialized views are not automatically updated with every data change. The data in the MV is brought up to date as specified when the view was created, e.g., fast refresh, complete refresh, etc. According to Oracle: 'A materialized view is automatically revalidated when it is referenced'. icon for materialized views indicates “needs compile”. You can check whether your view needs to be recompiled by checking the STALENESS column in USER_MVIEWS for your MV in question. The compile_status will be 'VALID' right after a refresh but before there is DML on the master table; it will be 'NEEDS_COMPILE' after there has been DML on the master table. Reply by John Dorlon The 2nd to last toolbar button on the Schema Browser gives you a legend of all of the icons. Each materialized view log is associated with a single base table. So when the materialized views will be 'automatically revalidated' and when they will not and we get ora-4045? Validity of the materialized view with respect to the objects upon which it depends: VALID - Materialized view has been validated without error, and no object upon which it depends has changed since the last validation. When you compile the MV, Oracle revalidates the query upon which the view is based. They must explicitly be refreshed, either on every… Materialized Views in Oracle; Introduction. The materialized view log resides in … As I understand it, the nested=>true option always refres View mode? … But what if it takes too long to refresh the materialized views? NEEDS_COMPILE - Some object upon which the materialized view depends NEEDS_COMPILE; COMPILATION_ERROR; The first two are normal behavior. last_refresh_date - date of the last refresh of the materialized view; compile_state - indicates validity of the materialized view (VALID/NEEDS_COMPILE/ERROR) Rows. This information comes from the COMPILE_STATE of DBA_MVIEWS. The status of 'COMPILATION_ERROR', however, is not expected. When it gets refreshed staleness state is 'NEEDS_COMPILE' and not showing recent updated data in the it. thanks in advance. One materialized view in my database is scheduled for refresh after every 1 hour. If the column shows "NEEDS_COMPILE", you need to execute above statement. A Refresh of a materialized view is a data operation. It seems the Materialized View needs to be compiled. RE: Schema Browser: Why do Materialized Views show INVALID when in Mat. The ! A materialized view can be refreshed automatically using the ON COMMIT method. os:rhel 6. * Materialized view that would go invalid... just so happens after every refresh attempt * View was FAST refreshable The problem was that the Materialized View Log was missing, so the refresh was failing. Refreshing nested materialized views Hi,When I have 2 materialized views (MV_1A and MV_1B) that are based on the same materialized view (MV_1) then using dbms_mview.refresh with the nested=>true option on 1 of those materialized views invalidates the other materialized view.
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