My app has models Person, Photo, Comment. A Comment has_many Photos and a Photo has_many People.
In the console, with a database with some data in it and the ActiveRecord logger sent to STDOUT ... First, to show what's in the data: irb(main):003:0> Photo.joins(:comments).order(:id).limit(2).map &:id D, [2014-08-05T18:19:10.528376 #24027] DEBUG -- : Photo Load (20.6ms) SELECT `photos`.* FROM `photos` INNER JOIN `comments` ON `comments`.`photo_id` = `photos`.`id` ORDER BY `photos`.`id` ASC LIMIT 2 => [1, 1] Photo.joins(:comments).order(:id).limit(2) returns the same photo twice, because it has two comments. That's what I want. (This is cut down from a much larger query where this behavior is actually useful.) Now for the problem: irb(main):001:0> Photo.joins(:comments).includes(:person).order(:id).limit(2).each { |f| puts f.person.username }; nil D, [2014-08-05T18:17:44.613676 #24027] DEBUG -- : Photo Load (0.6ms) SELECT `photos`.* FROM `photos` INNER JOIN `comments` ON `comments`.`photo_id` = `photos`.`id` ORDER BY `photos`.`id` ASC LIMIT 2 D, [2014-08-05T18:17:44.811715 #24027] DEBUG -- : Person Load (0.3ms) SELECT `people`.* FROM `people` WHERE `people`.`id` IN (1) user1 D, [2014-08-05T18:17:44.845897 #24027] DEBUG -- : Person Load (0.6ms) SELECT `people`.* FROM `people` WHERE `people`.`id` = 1 LIMIT 1 user1 Even though I said includes(:person), and it did cause ActiveRecord to issue the second query to get all the people, when I retrieve the second Photo's Person ActiveRecord has to query it again. With a production query with many more photos and people it's very slow. Is this a bug? Is includes not supported with a query that returns the same object more than once? Is there a way around the N + 1 queries? Thanks! -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-talk+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-talk@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/1279d510-aea0-4b03-83ac-d78ee8a2507d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.