There is no consistent definition in
computer science of sequential access or sequentiality. In fact, different sequentiality definitions can lead to different sequentiality quantification results. In spatial dimension, request size, stride distance, backward accesses, re-accesses can affect sequentiality. For temporal sequentiality, characteristics such as multi-stream and inter-arrival time threshold has impact on the definition of sequentiality. In
data structures, a data structure is said to have sequential access if one can only visit the values it contains in one particular order. The canonical example is the
linked list. Indexing into a list that has sequential access requires
O(
n) time, where
n is the index. As a result, many algorithms such as
quicksort and
binary search degenerate into bad algorithms that are even less efficient than their naive alternatives; these algorithms are impractical without
random access. On the other hand, some algorithms, typically those that do not have index, require only sequential access, such as
mergesort, and face no penalty. ==See also==