1 | #include "FunctionsConsistentHashing.h" |
---|---|
2 | #include <Functions/FunctionFactory.h> |
3 | |
4 | #include <consistent_hashing.h> |
5 | |
6 | namespace DB |
7 | { |
8 | |
9 | /// An O(1) time and space consistent hash algorithm by Konstantin Oblakov |
10 | struct YandexConsistentHashImpl |
11 | { |
12 | static constexpr auto name = "yandexConsistentHash"; |
13 | |
14 | using HashType = UInt64; |
15 | /// Actually it supports UInt64, but it is efficient only if n <= 32768 |
16 | using ResultType = UInt16; |
17 | using BucketsType = ResultType; |
18 | static constexpr auto max_buckets = 32768; |
19 | |
20 | static inline ResultType apply(UInt64 hash, BucketsType n) |
21 | { |
22 | return ConsistentHashing(hash, n); |
23 | } |
24 | }; |
25 | |
26 | using FunctionYandexConsistentHash = FunctionConsistentHashImpl<YandexConsistentHashImpl>; |
27 | |
28 | void registerFunctionYandexConsistentHash(FunctionFactory & factory) |
29 | { |
30 | factory.registerFunction<FunctionYandexConsistentHash>(); |
31 | } |
32 | |
33 | } |
34 | |
35 |