Drop duplicate likes and reset counts

migrations/005.limit-likes.up.sql

@@ -1,2 +1,26 @@
+--
 -- One like per-building, per-user
+--
+
+-- Drop duplicate likes
+DELETE FROM building_user_likes
+  WHERE building_like_id NOT IN (
+    SELECT min(building_like_id)
+    FROM building_user_likes
+    GROUP BY (building_id, user_id)
+  );
+
+-- Reset counts
+UPDATE buildings
+  SET likes_total = (
+    SELECT count(*)
+    FROM building_user_likes
+    WHERE buildings.building_id = building_user_likes.building_id
+  )
+  WHERE buildings.building_id in (
+      SELECT DISTINCT building_id
+      FROM building_user_likes
+  );
+
+-- Add constraint
 ALTER TABLE building_user_likes ADD CONSTRAINT building_like_once UNIQUE (building_id, user_id);