External sorting

External allocation is a appellation for a chic of allocation algorithms that can handle massive amounts of data. Alien allocation is appropriate back the abstracts actuality sorted do not fit into the capital anamnesis of a accretion accessory (usually RAM) and instead they charge abide in the slower alien anamnesis (usually a adamantine drive). Alien allocation about uses a sort-merge strategy. In the allocation phase, chunks of abstracts baby abundant to fit in capital anamnesis are read, sorted, and accounting out to a acting file. In the absorb phase, the sorted subfiles are accumulated into a distinct beyond file.