(un)pivot on Presto

20171104_2.md

Pivot

Query

SELECT
  uid,
  kv['c1'] AS c1,
  kv['c2'] AS c2,
  kv['c3'] AS c3
FROM (
  SELECT uid, map_agg(key, value) kv
  FROM vtable
  GROUP BY uid
) t

Result

uid  c1  c2  c3
---  --  --  --
101  11  12  13
102  21  22  23

Unpivot

Query

SELECT t1.uid, t2.key, t2.value
FROM htable t1
CROSS JOIN unnest (
  array['c1', 'c2', 'c3'],
  array[c1, c2, c3]
) t2 (key, value)

Result

uid  key  value
---  ---  -----
101   c1     11
101   c2     12
101   c3     13
102   c1     21
102   c2     22
102   c3     23