COMBINATIONS()

All functions > ARRAY > COMBINATIONS()

Returns all 2-element sub-groups of the input array as an array of 2-element arrays.

Signatures

Returns: All unordered pairs of elements (with replacement when duplicates appear in the input)

COMBINATIONS(array: ARRAY<T>) → ARRAY<ARRAY<T>>

Notes

• Always selects pairs of two elements (fixed arity)
• Supports scalar arrays, arrays of rows (ARRAY<ROW(...)>), and nested arrays (ARRAY<ARRAY<T>>)
• When the input has no duplicate values, each pair is an unordered subset
• Duplicate input values produce duplicate pairs in the result
• Returns an empty array when fewer than two elements are available

See also

• Array functions

Examples

SELECT
    -- String pairs without duplicates
    f1 := COMBINATIONS(ARRAY('foo', 'bar', 'baz')),
    -- Integer pairs
    f2 := COMBINATIONS(ARRAY(1, 2, 3)),
    -- Duplicate input values
    f3 := COMBINATIONS(ARRAY(1, 2, 2)),
    -- Empty input array
    f4 := COMBINATIONS(ARRAY()::BIGINT[]),
    -- Pairs of rows from ZIP
    f5 := COMBINATIONS(ZIP(ARRAY(1, 2, 3) AS x, ARRAY('a', 'b', 'c') AS y)),
    -- Pairs of nested sub-arrays
    f6 := COMBINATIONS(ARRAY(ARRAY(1, 2), ARRAY(3, 4), ARRAY(5, 6)))
;