HASH_COMBINE_COMMUTATIVE

hash_combine_commutative(value1, value2, ...)

Description

Performs commutative hash combination on multiple values. Unlike the regular hash_combine, the result of hash_combine_commutative is not affected by the order of parameters, meaning hash_combine_commutative(a, b, c) yields the same result as hash_combine_commutative(c, b, a). This function is commonly used in scenarios requiring hash computation for unordered sets.

Parameters

• value1, value2, ...: any type, the values to combine hashes for. At least one parameter is required.

Return Result

• bigint type
• Returns the commutative hash combination result of all input values
• The result is independent of parameter order

Examples

SELECT hash_combine_commutative(1, 2, 3); -- result: 10777284388

SELECT hash_combine_commutative(3, 2, 1); -- result: 10777284388

SELECT general_murmurhash3(bitmap_build(array(1L, 2L, 3L))), hash_combine_commutative( general_murmurhash3(3L), -- size general_murmurhash3(1L), general_murmurhash3(2L), general_murmurhash3(3L) ); -- result: -4327490212287121842 -4327490212287121842

SELECT general_murmurhash3(map(1, '2', 3, '4')), hash_combine( general_murmurhash3(size(map(1, '2', 3, '4'))), hash_combine_commutative( hash_combine(general_murmurhash3(1), general_murmurhash3('2')), hash_combine(general_murmurhash3(3), general_murmurhash3('4')) ) ); -- result: -7258238779908172255 -7258238779908172255

Notes

• hash_combine_commutative is commutative, meaning parameter order does not affect the result
• Difference from hash_combine: hash_combine considers parameter order, while hash_combine_commutative does not
• Commonly used for computing hash values of unordered data structures (such as set, bitmap, map)
• This function works together with general_murmurhash3 to implement hash computation for complex data structures
• Suitable for scenarios requiring deduplication or comparison of sets, where the order of elements is typically not important