D-index: Distance Index
D-index is an index structure which is able to search in data modelled as a metric space. This structure is static with respect to the number of buckets and levels, so the split functions must be designed before the D-index is instantiated and loaded with data. When this prerequisite is fulfiled, the D-index is capable of storing nearly "unlimited" number of data objects due to the elasticity of individual buckets. In particular, buckets are capable of storing theoretically any amount of data.