Materialized View Troubleshooting

The UC Davis Sakai isntance, Smartsite, uses materialzied views from the Banner Student Information System to provide course data. An initial set of mviews were created for the Sakai 2.1.x branch that worked well with the provider mechanism. Sakai 2.4.x uses the new Course Management system, which radically changes the data requirements from Banner. The initial set of mviews that were created to feed the Course Management system encountered problems when refreshing. This page will document the efforts to revise the materialized view definitions.

Troubleshooting Plan

Using the Sakai_Test schema on the Smartsite Development database, we will re-create all of the materialized views. The goal of the new MView creation process is the support of FAST REFRESH on as many Mviews as possible.

Testing

The mviews will be tested using the SYS.DBMS_SNAPSHOT.EXPLAIN_MVIEW(<Mview Name>); procedure. This procedure relies on the existence of a table called mv_capabilities_table in the mview schema. This table can be created via an admin oracle script at "oracle\product\ora10\rdbms\admin\utlxmv.sql". We would have preferred to use DBMS_ADVISOR.Tune_Mview, but do not have a license for it.

Performance Goals / Requirements

While our ultimate goal is to have all of the data in Course Management be an up-to-the-second copy of Banner data, we are aware that goal will not be reachable in most cases. The following table will list each of the mviews, an optimistic frequency in which the data in the source banner table is updated, and an acceptable time period in which the data might be allowed to stagnate.

Design Issues

• According to the Oracle 10G documentation, most of the mviews we are creating are "Materialized Views with Joins Only" and should be eligible for fast refresh. If necessary, I will try reformulating the mview and view definitions to use rowid based logs and mviews with rowid columns based on information from this page: http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14223/basicmv.htm#i1006803
• First roadblock: Canonical Courses. We are mapping this data from the SCBCRSE table, which has term information. In order to generalize it to canonical courses, a distinct clause is necessary. Distinct clauses will not work with mviews based on ROWID mview logs, and SCBCRSE doesn't have a primary key. So, in its current formulation, this mview will never fast refresh. That being said, we probably only need to run this mview once a month or so, and it stores less than ten thousand rows.

Status