CURRENT REFRESH AGE special register

The CURRENT REFRESH AGE special register specifies a time stamp duration value with a data type of DECIMAL(20,6).

The value of the CURRENT REFRESH AGE special register must be 0 - 99999999999999. The default value is determined by the dft_refresh_age database configuration parameter. You can change the value by issuing the SET CURRENT REFRESH AGE statement.

The value represents the maximum duration since a particular time-stamped event occurred to a cached data object. The cached data object can be used during this period to help optimize the processing of a query. An example of a time-stamped event is processing a REFRESH TABLE statement on a system-maintained REFRESH DEFERRED materialized query table.

For example, if the CURRENT REFRESH AGE special register has a value of 99999999999999 and the query optimization class is 2 or is greater than or equal to 5, the types of refresh deferred materialized query tables that you specify for the CURRENT MAINTAINED TABLE TYPES FOR OPTIMIZATION special register are considered during optimization of the processing of a dynamic SQL query.