External Mergesort
Previous sorts all assume ...
- efficient random access to
Item s
- which suggests that data is in arrays in memory
- which limits sortable data to what fits in memory
When the data is in disk files
- random access is inefficient (files are sequential access)
- but max data size is far less constrained
Because mergesort makes multiple sequential passes, it adapts well
as a sorting approach for files.
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