tom-lord

class AddPartialIndexOnDealershipIdAndExpiredAtToLeaseDeals < ActiveRecord::Migration[5.2]
  def change
    add_index :lease_deals, %i[dealership_id expired_at], where: 'expired_at IS NULL', algorithm: :concurrently
  end
end

tom-lord

 Bitmap Heap Scan on lease_deals  (cost=448.02..903.13 rows=5903 width=205)        
   Recheck Cond: ((dealership_id = 1234) AND (expired_at IS NULL))                                          
   Filter: ((updated_at < '2018-10-09 09:34:11.818701'::timestamp without time zone))
   ->  Bitmap Index Scan on index_lease_deals_on_dealership_id_and_expired_at  (cost=0.00..411.04 rows=6724 width=0)                                                                      
         Index Cond: (dealership_id = 1234) 

tom-lord

 Limit  (cost=0.11..4232.55 rows=1000 width=4)                   
   ->  Index Scan using lease_deals_pkey on lease_deals  (cost=0.11..3130311.24 rows=739600 width=4)
         Filter: ((expired_at IS NULL) AND (updated_at < '2018-10-09 09:26:33.507679'::timestamp without time zone) AND (dealership_id = 5678))

tom-lord

# Snippets taken from:
# https://github.com/rails/rails/blob/fc5dd0b85189811062c85520fd70de8389b55aeb/activerecord/lib/active_record/relation/batches.rb#L201

def in_batches(of: 1000, start: nil, finish: nil, load: false, error_on_ignore: nil)
  relation = self
  # ...
  batch_limit = of  
  # ...
  relation = relation.reorder(batch_order).limit(batch_limit)
  relation = apply_limits(relation, start, finish)

tom-lord

class LeaseDeal < ApplicationRecord
  def self.expire_all(time: Time.current, batch_size: 1000)
    ids = pluck(:id)
    ids.each_slice(batch_size) do |ids_slice|
      unscoped.where(id: ids_slice).update_all(expired_at: time)
    end
  end
end

tom-lord

class AddOrderedDealershipIdExpiredAtIndexToLeaseDeals < ActiveRecord::Migration[5.2]
  def change
    remove_index :lease_deals, name: :index_lease_deals_on_dealership_id_and_expired_at, algorithm: :concurrently

    add_index :lease_deals, %i[id dealership_id expired_at], where: 'expired_at IS NULL', using: :btree, order: { id: :asc }, algorithm: :concurrently
  end
end

tom-lord

# German rails_admin translation

de:
  admin:
    home:
      name: "Home"
    pagination:
      previous: "« Vor"
      next: "Zurück »"
      truncate: "…"

tom-lord

class Array
  def no_duplicates?
    tally.values.all? {|v| v == 1 }
  end
end

class Card
  attr_reader :picture, :suit

  def initialize(picture, suit)