Find :include causing n+1 queires


#1

Hey guys,

I just noticed one of my find calls is creating n+1 queries to be
run. The find looks like this:

 Class.find(:all,
    :include => [:user, :users],
    :conditions =>  {:id=> ids},
    :order => order )

This is on Rails 2.3.2.

First the class is queried, then the join table between class and
users, and then each user in the users collection is queried
individually. If I remove the :users from the include, then the users
aren’t loaded (until I hit them in the view).

I thought the whole point of :include is to avoid the n + 1 scenario?

Cheers,

Tim.


#2

On May 26, 6:32 am, Tim H. removed_email_address@domain.invalid wrote:

This is on Rails 2.3.2.

First the class is queried, then the join table between class and
users, and then each user in the users collection is queried
individually. If I remove the :users from the include, then the users
aren’t loaded (until I hit them in the view).

I thought the whole point of :include is to avoid the n + 1 scenario?

You should get one query per association loaded. If you are getting
more than that then you are probably accidentally loading an
association again. (for example be aware that the :include doesn’t
affect the association in the other direction). (I assume that in your
actual app Class is called something else - you may run into strange
problems if you try and override the core class Class with your own)

Fred