Priority mapping based on data accessed

You can prioritize activities based on what data the activity accesses during activity execution using the DATATAGINSC threshold.

Table spaces and storage groups can be assigned a numeric identifier, referred to as a data tag. The data tag for a table space can be either specified directly, or inherited from its storage group. Data tags can be used by DB2® WLM to identify which table spaces are being accessed by an activity. Using a combination of data tags and WLM controls, you can prioritize the work on your system based on which data is accessed. For example, if you have a table space IMPORTANT_TS containing critical data, you could choose to map any query that reads data from a table in this table space to a service class that is allocated a high percentage of the overall CPU on the system.

By using the DATATAGINSC threshold, you can map an activity to a different service class at run time when the activity accesses data that is assigned a particular data tag. For example, move any activity that reads data from a table space with data tag 3 to a different service class. Reactive prioritization is useful in those cases where the compiler is unable to accurately estimate the list of data tags for the activity. An example of such a case would be a query against a range partitioned table which uses parameter markers. The compiler cannot necessarily determine what table ranges are accessed in advance.