groupArraySample

groupArraySample(max_size[, seed])(x)

CREATE TABLE colors (
    id Int32,
    color String
) ENGINE = Memory;

INSERT INTO colors VALUES
(1, 'red'),
(2, 'blue'),
(3, 'green'),
(4, 'white'),
(5, 'orange');

SELECT groupArraySample(3)(color) as newcolors FROM colors;

┌─newcolors──────────────────┐
│ ['white','blue','green']   │
└────────────────────────────┘

-- Query with column name and different seed
SELECT groupArraySample(3, 987654321)(color) as newcolors FROM colors;

┌─newcolors────────────────┐
│ ['red','orange','green'] │
└──────────────────────────┘

-- Query with expression as argument
SELECT groupArraySample(3)(concat('light-', color)) as newcolors FROM colors;

┌─newcolors───────────────────────────────────┐
│ ['light-blue','light-orange','light-green'] │
└─────────────────────────────────────────────┘