ActiveRecord :: Relation转换为哈希缓慢

Question

i query 5000 records from the database, then converted into Hash, 'marker_id' as key, if 'marker_id' is the same, put together into Array. but it very slow when convert to Hash.

      total_attrs=MarkerAttr.where(marker_layer_id: layer.id)
      temp_attrs={}
      t=Time.now

      for ta in total_attrs
        if !temp_attrs.has_key?(ta.marker_id)
          temp_attrs["#{ta.marker_id}"]=[]
        end
        temp_attrs["#{ta.marker_id}"].push(ta)
      end
      p "to_hash_time::#{Time.now-t}"
      # TODO:: to_hash_time::1.563641124 

thanks

Answer 1

Hmm. I'm wondering if Enumerable#group_by will be any faster. Try this:

 total_attrs = MarkerAttr.where(marker_layer_id: layer.id).all
 temp_attrs = total_attrs.group_by(&:marker_id)