Presto – Convert Table into Map

I would like to convert the below table into a map with multiple key/value pairs

label_a	label_b
1	2
3	4
5	6

into

{‘label_a’ -> 1, ‘label_b’ -> 2}

{‘label_a’ -> 3, ‘label_b’ -> 4}

{‘label_a’ -> 5, ‘label_b’ -> 6}

What would be the easiest way to do this?

All the results I’ve found are scala/non-presto solutions and I’m not sure how it translates

Answer

You can construct a map with map_from_entries:

WITH data(label_a, label_b) AS (
    VALUES (1, 2), (3, 4), (5, 6)
)
SELECT map_from_entries(array[('label_a', label_a), ('label_b', label_b)])
FROM data