Controls how materialized views are used by the optimizer to answer queries efficiently.

Allowed values

Disabled, Fresh, Stale, N { Minute[s] | Hour[s] | Day[s] | Week[s] | Month[s] }

Default

Stale

Scope

Can be set for an individual connection, for an individual user, or for the PUBLIC group. Takes effect immediately.

Remarks

The materialized_view_optimization option lets you specify the circumstances under which the optimizer can use stale materialized views.

Data in a materialized view becomes stale when data in any of the base tables referenced by the materialized view is updated. You should consider the acceptable degree of data staleness when deciding the refresh frequency for the materialized view, and the time it takes to refresh the view, since the view is not available for querying during the refresh process. You should also consider whether it is acceptable for the database server to return results that may not reflect the current state of the database. You can choose from the following settings for this option:

When a query directly references a materialized view, the view is used regardless of staleness; the materialized_view_optimization option has no effect in this case.