Oracle materialized view refresh method

The refresh method can be incremental or a complete refresh. There are two incremental refresh methods , known as log-based refresh and partition change tracking (PCT) refresh. The incremental refresh is commonly called FAST refresh as it usually performs faster than the complete refresh.

So far I have created Materialized View mv_products_sales on prebuilt table and refresh on demand. The prebuilt table mv_products_sales is range partitioned on YYYYMM and created nicely. With this refresh method , only the changes since the last refresh are applied to the materialized view. In Oracle , if you specify REFRESH FAST for a single-table aggregate Oracle materialized view , you must have created a materialized view log for the underlying table, or the refresh command will fail.

Use the alter_mv_ refresh clause to change the default method and mode and the default times for automatic refreshes. If the contents of the master tables of a materialized view are modifie then the data in the materialized view must be updated to make the materialized view accurately reflect the data currently in its master table(s). A materialized view log was created for the employee table, so Oracle Database performs a fast refresh of the materialized view every days, beginning days after the materialized view is created. Because the materialized view conforms to the conditions for fast refresh , the database will perform a fast refresh. When building SQL views or query views on an Oracle database, you have the option of implementing a materialized view.

In contrast to a standard view , which has only a logical existence, a materialized view has a physical existence, and therefore it can be indexe analyze and managed like other database tables. How can I manually refresh a materialized view? How do I create an oracle materialized view? Why do we use materialized view in Oracle?

How to create Materialized View? Hi, I want to create a materialized view over a join of tables. YEAR, SUM(B.VALUE) FROM A, B WHERE B. YEAR And i want that my mview is always fresh, wich refresh method i have to use? I make many DML instructions over these tables.

Answer: Oracle 10g introduced the atomic refresh mechanism, whereby a materialized view is refreshed as a whole, as a single transaction. Now you might expect that an atomic refresh is faster than a manual rebuild or a refresh full, but this is not always the case. 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. Mike Ault Burleson Consulting. One of the suggested architectures to allow for rapid reporting without stressing the base tables is to use partitione refresh on commit, materialized views. For local materialized views , it chooses the refresh method which is estimated by optimizer to be most efficient.

All of the refreshed materialized views are updated to a single point in time. If the refresh fails for any of the materialized views , none of the materialized views are updated. If this parameter is set to false, then each of the materialized views is refreshed in a separate transaction. Upgrading from Oracle 9i to Oracle 10g will change the MV refresh behaviour. Oracle 10g will use the DELETE command to remove rows and a normal INSERT to repopulate it.

Materialized Views in Oracle. A materialized view , or snapshot as they were previously known, is a table segment whose contents are periodically refreshed based on a query, either against a local or remote table. Refresh a MV: EXEC dbms_mview.

Using materialized views against remote tables is the simplest way to achieve replication of data between sites.