dft_refresh_age - Default refresh age configuration parameter
This parameter specifies the default value for the CURRENT REFRESH AGE special register. 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.
- Configuration type
- Parameter type
- Default [range]
- 0 [0 - 99999999999999 (ANY)]
- Unit of measure
- yyyy is the number of years and can have a value of 0 - 9999.
- mm is the number of months and can have a value of 0 - 11.
- dd is the number of days and can have a value of 0 - 30.
- hh is the number of hours and can have a value of 0 - 23.
- mm is the number of minutes and can have a value of 0 - 59.
- ss is the number of seconds and can have a value of 0 - 59.
- nnnnnn is the number of fractional seconds. The fractional seconds portion of the value is ignored and therefore can be any value.
To set the dft_refresh_age configuration parameter to a value other than 0 or 99999999999999 (ANY), you must set the dft_mttb_types database configuration parameter to REPLICATION or NONE.
If the CURRENT REFRESH AGE has a value of 99999999999999 (ANY), and the QUERY OPTIMIZATION class has a value of two, five or more, REFRESH DEFERRED materialized query tables are considered to optimize the processing of a dynamic query.