Avoid N + 1 queries

[lucasas]

Hi guys,

First of all, thank you for the great work with this gem.

I have some performance issues here, because N + 1 queries using ancestry.

I have a model:

class Category < ActiveRecord::Base
   acts_as_tree
end

And I want to load all root categories loading all children of each one.

roots = Category.roots
roots.each { |r| r.children }

I want to execute only 2 queries here. I was looking for this into source code, but I didnt find it. Is there any plan to solve this performance issue?

Thank you.

[holstvoogd]

This is not a ancestry issue, but with your code. You iterate over an array build from a query, so yes, you'll get N+1 queries where N is the size of that array.
You could try something like:

Category.where(:ancestry => Catergory.roots.pluck(:id)).all

# or if you have depth caching on:
Category.where(:ancestry_depth_cache => 1).all

[lucasas]

I understood @holstvoogd, but it is not so object oriented, right?

[holstvoogd]

sure, but that is how ActiveRecord works. the .each call causes the first query to execute and then you have a simple array, so N queries.

[lucasas]

But when I use includes Active Record executes only 2 queries instead of N + 1. There is some plan to implement or have something equal to includes method? Thanks

[mjc]

If .includes() worked, rendering a collection wouldn't result in N+1 queries either.

[alexanderadam]

Sorry for reviving this issue but is there nowadays some integration for includes / eager_load / preload in ancestry?

[kbrock]

@alexanderadam I'm sorry to say that no. at this time there is no includes support

[alexanderadam]

What a pity. Thank you for responding so fast.
Could #440 stay open or is it possible to reopen this issue here so that everybody can see that this isn't solved yet?