Refresh Materialized Views

Published on September 23 2015 by LakshmiSaahul,Dhana Royal

Refresh Materialized Views

If a materialized view is configured to refresh on commit, you should never need to manually refresh it, unless a rebuild is necessary. Remember, refreshing on commit is a very intensive operation for volatile base tables. It makes sense to use fast refreshes where possible.

For on demand refreshes, you can choose to manually refresh the materialized view or refresh it as part of a refresh group.

The following code creates a refresh group defined to refresh every minute and assigns a materialized view to it.

BEGIN
   DBMS_REFRESH.make(
     name                 => 'SCOTT.MINUTE_REFRESH',
     list                 => '',
     next_date            => SYSDATE,
     interval             => '/*1:Mins*/ SYSDATE + 1/(60*24)',
     implicit_destroy     => FALSE,
     lax                  => FALSE,
     job                  => 0,
     rollback_seg         => NULL,
     push_deferred_rpc    => TRUE,
     refresh_after_errors => TRUE,
     purge_option         => NULL,
     parallelism          => NULL,
     heap_size            => NULL);
END;
/

BEGIN
   DBMS_REFRESH.add(
     name => 'SCOTT.MINUTE_REFRESH',
     list => 'SCOTT.EMP_MV',
     lax  => TRUE);
END;
/

A materialized view can be manually refreshed using the DBMS_MVIEW package.

EXEC DBMS_MVIEW.refresh('EMP_MV');

Rather than using a refresh group, you can schedule DBMS_MVIEW.REFRESH called using the Oracle Scheduler

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