Backwards N+1 problem

rubyonrails-talk
1

Hey, i’m running into an N+1 problem, but i don't exactly know how to :include in this situation. (controller code is at the bottom).

I'm trying to find all of the highest ranked definitions, and then render their associated phrases.

A Phrase has many definitions. A Definition has many children

I already have all the info i need stored in @definitions, so this should only require one SQL call, but unfortunately this line:

@Phrases << definition.phrase(:include => [:definitions => :children])

Doesn’t actually work.

Below is my controller code. Rails 2.1.0, Ruby 1.8.6…Thanks ahead of time

   def index       @definitions = Definition.find(:all, :include => [:children, :phrase], :limit => 10, :order => 'rank DESC')        @Phrases =        for definition in @definitions          @Phrases << definition.phrase(:include => [:definitions => :children])        end        @Phrases = @Phrases.uniq        if @Phrases != nil          @new_phrases = @Phrases.paginate(:page => params[:page], :order => 'word ASC', :per_page => 5)        end ## if @phrase !=nil     end ##def index

The full capture can be found under my Five Runs Account https://tuneup.fiveruns.com/runs/699

If you have any suggestions i would love for my main page to not take 5000 milliseconds to load : )

2

Hey, i’m running into an N+1 problem, but i don't exactly know how to :include in this situation. (controller code is at the bottom).

I'm trying to find all of the highest ranked definitions, and then render their associated phrases.

A Phrase has many definitions. A Definition has many children

I already have all the info i need stored in @definitions, so this should only require one SQL call, but unfortunately this line:

@Phrases << definition.phrase(:include => [:definitions => :children])

An easy way - Phrase.find :all, :include => [...], :conditions =>
["definitions.phrase_id in (?)", @definitions]

or something like @definitions = Definition.find :all, :include => [:phrase =>
{:definitions => :children}], :order => 'rank desc', :limit => 10 @phrases = @definitions.collect {|definition| definition.phrase}

might do the trick.

Fred

3

That knocked off about 1000ms, thanks for the help! Is it possible to re-arrange the order of your database all together??

When I take out the :order => 'rank desc' my sql call time gets cut in half, is there any way to tell RoR to automatically sort my definitions (in the DB) by rank descending??

I already have this code in my phrase.rb

"has_many :definitions, :order => 'rank DESC'"

but is it possible to have an entire model be automatically ordered by a specific column inside of the database?? In this case by rank.

4

That knocked off about 1000ms, thanks for the help! Is it possible to re-arrange the order of your database all together??

When I take out the :order => 'rank desc' my sql call time gets cut in half, is there any way to tell RoR to automatically sort my
definitions (in the DB) by rank descending??

I already have this code in my phrase.rb

"has_many :definitions, :order => 'rank DESC'"

but is it possible to have an entire model be automatically ordered
by a specific column inside of the database?? In this case by rank.

Nope. Or rather at the end of the day the database still needs to sort
it. An index on the column you are ordering by usually helps.

Fred.