Data marts and other data extracts - if they exist - may have to be refreshed on a regular basis. This needs to be done in order to ascertain exactly when such extracts need to be available, and how regularly they need to be refreshed. As with archiving it is advisable, if possible, to avoid making extract refresh part of the overnight window. Certainly if the archiving and data mart refresh are part of the overnight process, they need to be very tightly controlled, and their effect on the capacity of the server and the network needs to be well understood. If allowed to grow unrestricted, they will rapidly become a resource bottleneck, and will drive overnight processing into the business day.