Method and equipment for creating hash table

Abstract

The invention provides a method and equipment for creating a hash table. The method comprises following steps: determining subspace of at least two hash sub-tables according to space of the nth hash sub-table in N hash sub-tables of the hash table, wherein the size of the nth hash sub-table is non-positive integral power of 2 and sizes of subspace of at least two hash sub-tables are positive integral power of 2; mapping the current key value to one of sub-space of at least two hash sub-tables based on the nth pre-processed hash function used for mapping multiple key values to at least two sub-space of at least two hash sub-tables; generating an address of a hash bucket for the nth hash sub-table according to a hash function corresponding to one of subspace of the at least two hash sub-tables and the current key value; and storing the current key value into a hash sub-table of N hash sub-tables according to the number of free wafers corresponding to addresses of hash buckets for the N hash sub-tables generated by the N hash sub-tables. The method and equipment for creating the hash table have the capacities of reducing waste of space and decreasing cost of realization.

Description

technical field [0001] The invention relates to the communication field, in particular to a method and device for creating a hash table. Background technique [0002] The hash (hash) table has high search performance and is widely used in the field of communication technology. The 2-left hash algorithm divides a hash function into two independent hash functions hash1 and hash2. The two hash functions correspond to equal-sized hash subtables, and the hash functions hash1 and hash2 correspond to the two hash subtables. The maximum output is usually a positive integer power of 2, and the generated hash subtable space is also a positive integer power of 2, such as 2 megabytes (2097152), 4 megabytes (4194304), 8 megabytes (8388608), 16 megabytes (16777216), 32 megabytes (33554432), etc., so the 2-left hash table space is the sum of the two hash sub-table spaces, which is also a positive integer power of 2. However, the number of entries actually required is usually not a positi...

AI Technical Summary

Problems solved by technology

[0004] Use a large hash table to realize the space that is not a positive integer power of 2. Taking 32 mega-entries to realize the space of 24 million as an example, about 8 million space is wasted, that is, about 25% of the table entry space is redundant , causing a waste of space and increasing the cost of implementation

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