HAMMING_DISTANCE_APPROXIMATE

Description

Calculates Hamming distance between two byte vectors: the number of differing bits after bitwise XOR. NULL arrays or NULL elements raise an error.

Available in Doris 4.2 builds that include this function.Eligible Lance Top-N queries can use native approximate retrieval; other queries execute scalar kernels.

Syntax

HAMMING_DISTANCE_APPROXIMATE(<array1>, <array2>)

Parameters

Parameter	Description
<array1>	Integer array of TINYINT, SMALLINT, INT, or BIGINT, coerced to ARRAY. Every element must be in [0,255]; floating-point, decimal, and LARGEINT arrays are rejected.
<array2>	Integer array of TINYINT, SMALLINT, INT, or BIGINT, coerced to ARRAY. Every element must be in [0,255]; floating-point, decimal, and LARGEINT arrays are rejected. The two arrays must have the same length.

Return Value

Returns FLOAT; smaller means closer. Two empty arrays return 0; N-byte vectors have a maximum distance of 8N.Unequal lengths, NULL arrays, or NULL elements raise an error rather than return NULL.Out-of-range elements also raise an error.Native candidate eligibility, numerical precision, and NULL/NaN behavior can differ from scalar execution; see automatic search.

Example

SELECT HAMMING_DISTANCE_APPROXIMATE([0,255,170], [255,0,85]) AS value;

value
24

SELECT HAMMING_DISTANCE_APPROXIMATE([], []) AS value;

value
0

SELECT HAMMING_DISTANCE_APPROXIMATE(NULL, [0,1]);

ERROR: First argument for function hamming_distance_approximate cannot be null

SELECT HAMMING_DISTANCE_APPROXIMATE([0,NULL], [0,1]);

ERROR: First argument for function hamming_distance_approximate cannot have null

SELECT HAMMING_DISTANCE_APPROXIMATE([256], [0]);

ERROR: Hamming vector elements must be integers in [0, 255]