• the dominant cost   (given current disk technology)

• measured in terms of pages read, not records read

CPU cost

• primarily related to computing distance measure D(v_obj , v_q)

• can be relatively expensive for some QBIC features

Space

• need to store data (feature vectors) within page-size chunks

• access methods typically require additional disk space
  (which can be anywhere from 10% extra to >100% extra)

• intermediate data structures in memory?