Rails 3 taking a long time to load the results - ruby-on-rails

Question

My rails application has to query through a database which has lacks of rows and display the matching results. My code is working perfectly but its dead slow ,its taking a very long time to show the results.I am using ruby 1.9.3 and rails 3.2.13 and "Webrick" server.I am sure there is some problem . Is there any way I can resolve this .I have two tables called coordinates and tweets.
My code for the controller
require 'will_paginate/array'
class TweetsController<ApplicationController
def index
city = params[:show]
search_term = params[:text]
search_term.gsub!(/\s/, '%')
city_coordinates = Coordinates.where('city=?', city)
if (city_coordinates.count == 1 && city_coordinates.first.valid_location?)
#tweets = ((Tweets.for_coordinates(city_coordinates.first) & Tweets.where("tweet_text LIKE?" , "%#{search_term}%"))).paginate(page: params[:page], per_page:5)
elsif(city_coordinates.count!=1)
#tweets = ((Tweets.for_user_location(city) & Tweets.where("tweet_text LIKE?" , "%#{search_term}%"))).paginate(page: params[:page], per_page: 5)
else
Tweets.where("tweet_text LIKE? ", "%#{search_term}%").paginate(page: params[:page], per_page: 5)
end
end
end
My code for the model
class Tweets<ActiveRecord::Base
attr_accessible :id, :tweet_created_at, :tweet_id, :tweet_text, :tweet_source, :user_id, :user_name, :user_sc_name, :user_loc, :user_img, :longitude, :latitude, :place, :country
def self.for_coordinates(coordinates)
bbox = { min_lat: coordinates.latitude - 1.0, max_lat: coordinates.latitude + 1.0,
min_lng: coordinates.longitude - 1.0, max_lng: coordinates.longitude + 1.0
}
Tweets.where("(longitude BETWEEN ? and ?) AND (latitude BETWEEN ? and ?) OR (user_loc LIKE ?) " ,
bbox[:min_lng], bbox[:max_lng], bbox[:min_lat], bbox[:max_lat], "%#{coordinates.city}%" )
end
def self.for_user_location(city)
#tweets= Tweets.where("user_loc LIKE ?", "%#{city}%")
end
end
My code for the view
<%= will_paginate #tweets %>
<% #tweets.each do |tweets| %>
<ul>
<li><%= tweets.id %></li>
<li><%= tweets.tweet_created_at %></li>
<li><%= tweets.tweet_source %></li>
<li><%= tweets.tweet_text %></li>
<li><%= tweets.user_id %></li>
<li><%= tweets.user_name %></li>
<li><%= tweets.user_sc_name %></li>
<li><%= tweets.user_loc %></li>
<li><%= tweets.user_img %></li>
<li><%= tweets.longitude %></li>
<li><%= tweets.latitude %></li>
<li><%= tweets.place %></li>
<li><%= tweets.country %></li>
<% end %>
</ul>
It has two search boxes ,one for the tweet query and another for the city,It has to display tweets for a particular city.But its very slow .I am not able to find the reason if it is due to inefficient coding or wrong choice of server or some other reasons .It uses Mysql database.

Answer 1

Your issue is with the union of two queries:
#tweets = (
(
Tweets.for_coordinates(city_coordinates.first) &
Tweets.where("tweet_text LIKE?" , "%#{search_term}%")
)
).paginate(page: params[:page], per_page:5)
What this does is:
Retrieve all tweets for the city coordinates into an in-memory array
Retrieve all tweets where the text matches the search term into an in-memory array
Concatenates the arrays from 1. and 2.
Paginates these results
What you want to do instead is:
Filter for tweets that match the city coordinates AND the search term
Paginate the results
Retrieve the paginated results
You'll want something more like this:
#tweets = Tweets.for_coordinates(city_coordinates.first).
where('tweet_text like ?', "%#{search_term}%").
paginate(page:params[:page], per_page:5)