Problems using controller on postgres DB on AWS RDS from Heroku app - ruby-on-rails

Question

I've setup a postgres DB to use postgis for a Heroku App I have, running on Ruby on Rails.
My steps have been:
Create RDS DB running pg 9.4.9
Enable rds.force_ssl on RDS Parameter Group.
Backup and load my Heroku database into new postgres DB.
Download Amazon RDS CA Certificate and place it under config/amazon-rds-ca-cert.pem.
Add gem 'activerecord-postgis-adapter' to my gem file.
Update database.yml file to the below:
:
default: &default
adapter: postgis
encoding: unicode
pool: 5
production:
<<: *default
encoding: utf8
database: <%= ENV['RDS_DB_NAME'] %>
username: <%= ENV['RDS_USERNAME'] %>
password: <%= ENV['RDS_PASSWORD'] %>
host: <%= ENV['RDS_HOSTNAME'] %>
port: <%= ENV['RDS_PORT'] %>
postgis_extension: postgis
schema_search_path: public,postgis
Update DATABASE_URL parameter on Heroku to postgres://myuser:mypassword#mydbinstance.xxxxxxxxxxx.us-west-2.rds.amazonaws.com/mydbname?sslmode=verify-full&sslrootcert=config/amazon-rds-ca-cert.pem
Additional steps in this very helpful question: Enabling Ruby PostGIS support on Heroku
Push updated code and access my App.
When I try to access the database to verify connectivity it works ok:
nc -zv mydbinstance.xxxxxxxx.us-west-2.rds.amazonaws.com 5432
Connection to mydbinstance.xxxxxxxxx.us-west-2.rds.amazonaws.com 5432 port [tcp/postgresql] succeeded!
and when I navigate on the app I am able to see the results of queries. However, when I try to use a model that uses postgis, somehow my connections don't work correctly. Here's my Controller's code, which stores lat, lng pairs with bus stop information, and finds the ones close to a point given in parameters:
class TransitStopsController < ApplicationController
def create
end
def show
#transit_stop = TransitStop.find(params[:id])
#transit_routes = #transit_stop.transit_routes
end
def get_nearby_stops
radius_in_meters = params[:radius_in_meters].nil? ? 3219 : params[:radius_in_meters]
#nearby_stops = TransitStop.close_to(params[:lat], params[:lng], radius_in_meters)
end
end
My Model:
class TransitStop < ActiveRecord::Base
has_many :transit_stops_transit_routes, foreign_key: "onestop_id", class_name: "TransitStopsTransitRoute"
has_many :transit_routes, through: :transit_stops_transit_routes, foreign_key: "route_onestop_id", class_name: "TransitRoute"
validates_uniqueness_of :onestop_id
#Get transit stops close to a given lat, lng pair. Default distance = 2 miles
scope :close_to, -> (lat, lng, distance_in_meters = 3219) {
where(%{
ST_DWithin(
ST_GeographyFromText(
'SRID=4326;POINT(' || transit_stops.lng || ' ' || transit_stops.lat || ')'
),
ST_GeographyFromText('SRID=4326;POINT(%f %f)'),
%d
)
} % [lng, lat, distance_in_meters])
}
end
and my View (get_nearby_stops.jbuilder):
json.nearby_stops #nearby_stops do |transit_stop|
json.region_id transit_stop.region_id
json.lat transit_stop.lat
json.lng transit_stop.lng
json.onestop_id transit_stop.onestop_id
json.name transit_stop.name
json.osm_way_id transit_stop.osm_way_id
json.osm_way_id transit_stop.served_by_vehicle_types
json.timezone transit_stop.timezone
json.wheelchair_boarding transit_stop.wheelchair_boarding
json.created_or_updated_in_changeset_id transit_stop.created_or_updated_in_changeset_id
json.transit_routes transit_stop.transit_routes
end
Routes.rb has line added to access method:
get 'transit_stops/get_nearby_stops' => 'transit_stops#get_nearby_stops'
When I try to access this via: https://myherokuapp.herokuapp.com/transit_stops/get_nearby_stops.json?lat=-122.49766&lng=37.71677
All I get is a message:
Application Error
An error occurred in the application and your page could not be served. If you are the application owner, check your logs for details.
When I look at my heroku logs all I see is a timeout error:
app[web.1]: Processing by TransitStopsController#get_nearby_stops as JSON
app[web.1]: Parameters: {"lat"=>"-122.49766", "lng"=>"37.71677"}
heroku[router]: at=error code=H12 desc="Request timeout" method=GET path="/transit_stops/get_nearby_stops.json?lat=-122.49766&lng=37.71677" host=myherokuapp.herokuapp.com request_id=1e081fdf-d0ce-4000-a6b4-4e75c176b8a2 fwd="10.0.0.1" dyno=web.1 connect=0ms service=30001ms status=503 bytes=0
The AWS Error Logs show nothing.
The strange thing to me is that I am able to perform the same query by connecting to Heroku's rails console:
irb(main):001:0> TransitStop.close_to(-122.49766,37.71677,5000)
=> #<ActiveRecord::Relation [#<TransitStop region_id: 1, lat: #<BigDecimal:7fe69f6c95c0,'-0.122504106E3',18(18)>...
...
etc
So at this point I don't understand what's causing this controller to fail only when I access it through my view, but not through console? Should the database url be different if I use postgis methods?
Any help would be highly appreciated.
EDIT: I've tested the show method of my controller, and it works ok:
app<a class="jive-link-external" href="http://web.1">http://web.1</a>: Started GET "/transit_stops/s-9q8ys6puje-655johnmuirave.json" for 159.16.243.2 at 2016-11-12 19:55:16 +0000
app<a class="jive-link-external" href="http://web.1">http://web.1</a>: Processing by TransitStopsController#show as JSON
app<a class="jive-link-external" href="http://web.1">http://web.1</a>: Parameters: {"id"=>"s-9q8ys6puje-655johnmuirave"}
herokurouter: at=info method=GET path="/transit_stops/s-9q8ys6puje-655johnmuirave.json" host=myapp.herokuapp.com request_id=15814367-5235-484b-bff9-7727a2349dd0 fwd="10.0.0.1" dyno=web.1 connect=0ms service=329ms status=200 bytes=1385
app<a class="jive-link-external" href="http://web.1">http://web.1</a>: Rendered transit_stops/show.json.jbuilder (107.3ms)
app<a class="jive-link-external" href="http://web.1">http://web.1</a>: Completed 200 OK in 217ms (Views: 6.7ms | ActiveRecord: 207.4ms)<br class="jive-newline" />
Which to me translates to perhaps there being some problem in the database to perform the query I'm doing? The query itself should be fast, as when I test it in console I always get a response almost immediately, but perhaps something about the configuration of the database needs to be changed?

Answer 1

Just for other people to see, my problem was that after the query, my view was also producing several additional queries, because the field
transit_stop.transit_routes
is a relationship to a different table. Thus, for every resulting stop the database was performing many other queries for every result I got. Since my query was returning several hundred results, the final view performed several hundred additional queries which caused a lot of overhead to my db.
To detect this I updated log_statement = all to my db parameter group, so that I could see all activity coming into the database. I've updated my query to make it more efficient by reducing the number of results to only the n nearest ones, with a maximum of 10, as I don't really have any use on getting so many results.