BUCKET

bucket(numBuckets, col)

Description

Computes a hash bucket number based on a specified number of buckets and a column value. This function uses a hash algorithm to map the input value to an integer within the range [0, numBuckets), commonly used in data partitioning and distributed computing scenarios.

Parameters

• numBuckets: int type, the number of buckets, must be greater than 0
• col: any type, the column value for which to compute the hash bucket

Return Result

• int type
• The return value range is [0, numBuckets)
• Returns NULL if the input value is NULL

Examples

SELECT bucket(10, 'test'); -- result: 4

SELECT bucket(10, 123); -- result: 4

Notes

• The BUCKET function uses a hash algorithm to ensure the same input value is always mapped to the same bucket
• Commonly used in scenarios such as data partitioning, sampling, and load balancing
• The returned bucket number starts from 0, with a maximum value of numBuckets - 1
• The same value of different types (e.g., the integer 1 and the string '1') may be mapped to different buckets
• This function is deterministic: the same input always produces the same output.