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
This parameter specifies a time stamp value with a data type of DECIMAL(20,6). The value must be 0 - 99999999999999 or a valid time stamp within that range. The valid format for the range is yyyymmddhhmmss.nnnnnn, where:
  • 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.
You do not have to include the leading zeros for the entire value or the trailing fractional seconds. However, individual elements that have another element to the left must include the zeros. For example, to represent 1 hour, 7 minutes, and 5 seconds, use 10705.

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.