Re: Most efficient way to insert without duplicates

[Chris Curvey <chris@xxxxxxxxxxxxxxx>]

INSERT INTO persona_followers(service_id, follower_id, valid_at)
  SELECT service_id, follower_id, NOW()
  FROM (SELECT DISTINCT service_id, follower_id FROM import) AS import
  WHERE NOT EXISTS(SELECT * FROM persona_followers WHERE import.service_id = persona_followers.service_id AND import.follower_id = persona_followers.follower_id);

I'm wondering if you have an unneeded level of nesting. (I don't know if it would make any difference, but it might).

INSERT INTO persona_followers(service_id, follower_id, valid_at)
SELECT DISTINCT service_id, follower_id, now()

FROM import
WHERE NOT EXISTS(SELECT * FROM persona_followers WHERE import.service_id = persona_followers.service_id AND import.follower_id = persona_followers.follower_id);