Oracle materialized view log

How do I create an oracle materialized view? How to create Materialized View? When to use materialized view? Can we use create or replace materialized view?

A materialized view log is located in the master database in the same schema as the master table. A master table can have only one materialized view log defined on it.

Use the ALTER MATERIALIZED VIEW LOG statement to alter the storage characteristics or type of an existing materialized view log. You cannot create a materialized view log for a table in the schema of the user SYS. Specify the schema containing the materialized view log and its master table.

Using materialized views against remote tables is the simplest way to achieve replication of data between sites. To fast refresh a materialized join view , you must create a materialized view log for each of the tables referenced by the materialized views. This is called fast refreshing.

Before a materialized view can perform a fast refresh however it needs a mechanism to capture any changes made to its base table. Use the WITH clause to indicate whether the materialized view log should record the primary key, rowi object I or a combination of these row identifiers when rows in the master are changed.

You can also use this clause to add a sequence to the materialized view log to provide additional ordering information for its records. The complication comes from the lag between the last refresh of the materialized view and subsequent DML changes to the base tables. The frequency of this refresh can be configured to run on-demand or at regular time intervals. Simply truncating the Materialized View log may lead to otherwise healthy and up-to-date MViews to loose the capability to FAST REFRESH (due to the mismatch in last refresh timestamps). As a consequence, costly full refreshes would be required on many (potentially large) MViews, in turn causing delays in availability. or to customize your list.

Automatically the data from the log table will be purged. For reference please see the below output. The owner of XYZ has to GRANT SELECT ON MLOG$_XYZ to the account that will be creating a Fast Refresh MV that needs to read the MV Log. To see all views in a database you must query DBA_MVIEWS or DBA_SNAPHOTS. Oracle creates a table MLOG$_XYZ.

Yes, that is suspicious. Materialized view log is a table associated with the master table of a materialized view. Create the materialized view logs (MVL) If the materialized view (MV) will be refreshed by applying the latest changes the MVL must be created. The MVL are tables situated on the source schema which keep the latest changes. It has to be created where the base table DEPT is present.

I am not using it anymore. 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. The materialized view log does not get cleared after the fast refresh. In the example below note how the log table is empty after the refresh.

CREATE MATERIALIZED VIEW to MV_USER where MV_USER is the OWNER of the MATERIALIZED VIEW. Connect as that same MV_USER. To fix your broken jobs, connect as the MV_USER (owner of the MV).

Can you use dbms_metadata for extracting the materialized view source code? DDL for materialized views , but it needs formatting.