alekseyl

proxy_cache_path /path/to/cache levels=1:2 keys_zone=my_cache:10m max_size=10g
                 inactive=60m use_temp_path=off;

server {
    ...
    location / {
        proxy_cache my_cache;
        proxy_cache_revalidate on;
        proxy_cache_min_uses 1;
        proxy_cache_use_stale error timeout updating http_500 http_502 http_503 

alekseyl

class Product <ActiveRecord::Base
 after_commit :prerender
 def prerender
  keys = [ [:user, :admin, :moderator, nil], [:ru, :en ] ]
  keys.pop.product(*keys).each do |lr|
   # lr - locale + role
   ApplicationController.render(
    assigns: {locals: {product: self, role: lr[1], locale: lr[0]} },
    inline: '<% render partial: "products/product", locals: @locals %>')
    #of course products/_product.html.slim must start with

alekseyl

# nil means current_user is empty i.e. it's a guest
keys = [ [:user, :admin, :moderator, nil], [:ru, :en ] ]
# all combination of keys:
all_flatten_keys = keys.pop.product(*keys)
# [[:ru, :user], [:ru, :admin], [:ru, :moderator], [:ru, nil], 
#  [:en, :user], [:en, :admin], [:en, :moderator], [:en, nil]]

alekseyl

# DB way
Shipment.scope
        .joins(purchase: :product)
        .select(["shipments.*","sum(purchases.items_count*products.gross_weight) as gross_weight"])
        .group("shipments.id")