Help optimizing get all children query (ActiveRecord/Ruby/Rails)

This is just a quick question on performance in an sql query using ruby and rails.

Basically I have a parent model and a bunch of children which have the variable of parent_ID. I first gather all the parents with a specific condition and then I cycle through each parent finding any children that match.

Unfortunately this is incredibly slow and I was wondering if开发者_JS百科 theres any help going in optimizing it.

 @parents = Parent.where(:parent_id => 3) #This is passed in from params

 @childrenArray =[]
    @parents.each_with_index do |parent, index|
      #TOOSLOW
      @childrenArray[index] = Child.find(:all,:order=>"id",:conditions =>{:parent_ID=> parent.id})
  end

One thing I thought is perhaps I should make an array of all the parent Ids to be searched and then do something like

child.find_by_parent_ID(myarrayofnumbershere)

However I don't know if this would be any better.

Any help or advice appreciated.

---

I'm very new to SQL and ruby. I'm aware a table joins would have been ideal here but I think I'm a bit late in my development to try it now. Also I need to serve up 2 seperate arrays. one of the parents and one of the children.

---

Try using the include method, like so:

@parents = Parent.where(:parent_id => 3).include(:children)

Now rails will have fetched the associated children and you should be able to loop over @parents and access their children without additional queries, like so:

@parents.each do |p|
  puts "#{p}'s children: #{p.children}"
end