Extendible Hashing
نویسندگان
چکیده
DEFINITION Extendible Hashing is a dynamically updateable disk-based index structure which implements a hashing scheme utilizing a directory. The index is used to support exact match queries, i.e. find the record with a given key. Compared with the B+-tree index which also supports exact match queries (in logarithmic number of I/Os), Extendible Hashing has better expected query cost O(1) I/O. Compared with Linear Hashing, Extendible Hashing does not have any overflow page. Overflows are handled by doubling the directory which logically doubles the number of buckets. Physically, only the overflown bucket is split.
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تاریخ انتشار 2009