Efficient cross-trees for external memory
Roberto Grossi, Giuseppe Italiano · DIMACS series in discrete mathematics and theoretical computer science · 1999
. We describe efficient methods for organizing and maintaining large multidimensional data sets in external memory. This is particular important as access to external memory is currently several order of magnitudes slower than access to main memory, and current technology advances are likely to make this gap even wider. We focus particularly on multidimensional data sets which must be kept simultaneously sorted under several total orderings: these orderings may be defined by the user, and may also be changed dynamically by the user throughout the lifetime of the data structures, according to the application at hand. Besides standard insertions and deletions of data, our proposed solution can perform efficiently split and concatenate operations on the whole data sets according to any ordering. This allows the user: (1) to dynamically rearrange any ordering of a segment of data, in a time that is faster than recomputing the new ordering from scratch; (2) to efficiently answer queries rel...