Disk space requirements   Since materialized views contain a duplicate of data from base tables, you may need to allocate additional space on disk for the database to accommodate the materialized views you create. Careful consideration needs to be given to the additional space requirements so that the benefit derived is balanced against the cost of using materialized views.

Maintenance costs and data freshness requirements   The data in materialized views needs to be refreshed when data in the underlying tables changes. The frequency at which a materialized view needs to be refreshed needs to be determined by taking into account potentially conflicting factors such as:

Use in optimization   You should verify that the optimizer considers the materialized views when executing a query. You can see the list of materialized views used for a particular query by looking at the Advanced Details window of the query's graphical plan in Interactive SQL. See Reading execution plans, and Improving performance with materialized views.

You can also use Application Profiling mode in Sybase Central to determine whether a materialized view was considered during the enumeration phase of a query by looking at the access plans enumerated by the optimizer. Tracing must be turned on, and must be configured to include the OPTIMIZATION_LOGGING tracing type, to see the access plans enumerated by the optimizer. See Application profiling, and Choosing a diagnostic tracing level.