example postgresql bulk upsert query (from http://blog.cartodb.com/faster-data-updates-with-cartodb )

gistfile1.txt

WITH
-- write the new values
n(ip,visits,clicks) AS (
  VALUES ('192.168.1.1',2,12),
         ('192.168.1.2',6,18),
         ('192.168.1.3',3,4)
),
-- update existing rows
upsert AS (
  UPDATE page_views o
  SET visits=n.visits, clicks=n.clicks
  FROM n WHERE o.ip = n.ip
  RETURNING o.ip
)
-- insert missing rows
INSERT INTO page_views (ip,visits,clicks)
SELECT n.ip, n.visits, n.clicks FROM n
WHERE n.ip NOT IN (
  SELECT ip FROM upsert
);