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Pruning Tasks and Dependencies in the DAC

A task is a command that is used to populate a certain table or tables. A task can have prerequisite tasks that need to be executed prior to its own execution. These are defined as dependency rules. There are mandatory and optional dependencies. For example, Load into Activity Fact has a mandatory dependency on Extract into Activity Fact, but has optional dependency on all the tasks that load the dimensions. This is because loading of the Activity Fact table cannot be accomplished until its extract is done. However, if the dimension tables are not absolutely necessary, that is, if part of the pruning process eliminates a certain table from the initial list of tables selected, then the load task will not wait for that optional tasks.