Pick a random attribute from group in Redshift

Question

I have a data set in the form.

id  |   attribute
-----------------
1   |   a
2   |   b
2   |   a
2   |   a
3   |   c

Desired output:

Answer 1

I haven't tested this query, but these functions are supported in Redshift:

select id, arrary_to_string(array(select attribute from mydataset m where m.id=d.id),',') from mydataset d