Question

Right now I have a table called Campaigns that has many Hits, if I call say:

Campaign.find(30).hits

Which takes 4 seconds, or 4213 ms.

If I call this instead:

 campaign = Campaign.find(30) campaign.hits.count 

Does it still load all of the hits, then count? Or does it see I am counting and avoids loading all of the hits? (Which is currently 300,000+ rows).

I am trying to figure out a smart way to load/count my hits. I am thinking about adding a method to my Campaign.rb model, like:

 def self.total_hits    find :first, :select => 'COUNT(id) as hits', :conditions => ['campaign_id = ?', self.id] end 

I know that query won’t load from the hits table, but that is just an example of counting it from a self made query, apposed to Ruby on Rails doing this for me.

Would this memcache query be more effecient? (I have it running, but doesn’t seem to be any better/faster/slower, just the same speed.)

 def self.hits     Rails.cache.fetch('Campaign_Hits_#{self.campaign_id}', :expires_in => 40) {       find(:first, :select => 'COUNT(id) as hits', :conditions => ['campaign_id = ?', self.campaign_id]).hits     } end 

Any suggestions would be great!

Answer 1

How about:

Campaign.find(30).hits.count 

You might also consider adding the following in hit.rb (assuming a one-to-many relationship between campaigns and hits).

belongs_to :campaign, :counter_cache => true 

You then need a column in the campaigns table called hits_count. This will avoid hitting hits altogether if you’re only getting the count.

You can check the API for the full rundown.