External sorting

number of passes: 1 + ⌈ l o g 2 ( N / M ) ⌉ 1+ \lceil log_2 (N/M) \rceil 1+⌈log2​(N/M)⌉ seek time: O(number of passes) a k-way merge number of passes: 1 + ⌈ l o g k ( N / M ) ⌉ 1+ \lceil log_k (N/M) \

>>阅读原文<<