What is Oracle materialized view log?

In an Oracle database, a materialized view log is a table associated with the master table of a materialized view. When master table data undergoes DML changes (such as INSERT, UPDATE, or DELETE), the Oracle database stores rows describing those changes in the materialized view log.

How do I create a log for materialized view?

CREATE MATERIALIZED VIEW LOG

  1. Use the CREATE MATERIALIZED VIEW LOG statement to create a materialized view log, which is a table associated with the master table of a materialized view.
  2. create_materialized_vw_log::=
  3. logging_clause::=
  4. new_values_clause::=
  5. schema.
  6. table.

Can we create materialized view log on a view?

A materialized view log cannot be created using a materialized view as the table or for tables in cache groups. A materialized view log cannot be altered to add or drop columns. You can specify only one PRIMARY KEY clause, one ROWID clause and one column list for a materialized view log.

What’s the purpose of a materialized view log when is it required?

A materialized view log is required on a master if we want to fast refresh materialized views based on the master.

How do I check materialized view refresh errors?

To check on when the mview was last refreshed: select owner, mview_name, last_refresh_date from dba_mviews; Therefore, if you are refreshing the mview every morning, you can set up a scheduler job to send an email if the mview was or was not refreshed that morning (based on the results of the above query).

How do I drop materialized view log?

To drop a materialized view log, you must have the privileges needed to drop a table. Specify the schema containing the materialized view log and its master table. If you omit schema , then Oracle Database assumes the materialized view log and master table are in your own schema.

How do you get DDL of a materialized view in Oracle?

“how to get ddl for materialized view” Code Answer

  1. — Views (use USER_VIEWS or DBA_VIEWS if needed):
  2. SELECT TEXT FROM ALL_VIEWS WHERE upper(VIEW_NAME) LIKE upper(‘%VIEW_NAME%’);
  3. — Or:
  4. SELECT dbms_metadata.
  5. ​
  6. — Materialized views (use USER_VIEWS or DBA_VIEWS if needed):

How do I speed up a materialized view refresh?

– Use super-fast solid-state disks – The easiest and most reliable way is to speed-up a materialized view refresh is to move the target tables and MV’s to SSD. SSD runs several hundred times faster than platter disk, and it plops right in, just a few hours to install.

Do materialized views automatically update?

Unlike indexes, materialized views are not automatically updated with every data change. They must explicitly be refreshed, either on every commit, on a periodically time schedule or – typically in data warehouses – at the end of an ETL job.

Why do we use materialized view in Oracle?

To encapsulate complex queries that are core to an operation so that multiple applications can benefit from consistent results.

  • To hide changes in table schema from older applications that may balk at the new schema version.
  • To create a logical table with calculated values that are based on data from multiple tables.

    • How to find stale materialized views in Oracle?

    – One row represents one materialized view in a database – Scope of rows: (A) all materialized views, with their definition, accessible to the current user in Oracle database, (B) all materialized views, with their definition, in Oracle database – Ordered by schema name, materialized view name

    How to create Materialized View log on the remote database?

    – Verify the privileges of the user who will own the materialized views – Connect to the user who will own the materialized views and create the views along with the database link keeping the following in mind: Using the FORCE parameter will allow – On the master instance, set up the materialized view log, which will allow the fast refresh to work.

    How to update a materialized view directly?

    – To change its storage characteristics – To change its refresh method, mode, or time – To alter its structure so that it is a different type of materialized view – To enable or disable query rewrite Note: The keyword SNAPSHOT is supported in place of MATERIALIZED VIEW for backward compatibility.

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