Move status counters to separate table, count replies (#8104)

* Move status counters to separate table, count replies

* Migration to remove old counter columns from statuses table

* Fix schema file

db/migrate/20180812162710_create_status_stats.rb

@@ -0,0 +1,12 @@
+class CreateStatusStats < ActiveRecord::Migration[5.2]
+  def change
+    create_table :status_stats do |t|
+      t.belongs_to :status, null: false, foreign_key: { on_delete: :cascade }, index: { unique: true }
+      t.bigint :replies_count, null: false, default: 0
+      t.bigint :reblogs_count, null: false, default: 0
+      t.bigint :favourites_count, null: false, default: 0
+
+      t.timestamps
+    end
+  end
+end

db/migrate/20180812173710_copy_status_stats.rb

@@ -0,0 +1,19 @@
+class CopyStatusStats < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def up
+    safety_assured do
+      execute <<-SQL.squish
+        INSERT INTO status_stats (status_id, reblogs_count, favourites_count)
+        SELECT id, reblogs_count, favourites_count
+        FROM statuses
+        ON CONFLICT (status_id) DO UPDATE
+        SET reblogs_count = EXCLUDED.reblogs_count, favourites_count = EXCLUDED.favourites_count
+      SQL
+    end
+  end
+
+  def down
+    # Nothing
+  end
+end

db/post_migrate/20180813113448_copy_status_stats_cleanup.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class CopyStatusStatsCleanup < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def change
+    safety_assured do
+      remove_column :statuses, :reblogs_count, :integer, default: 0, null: false
+      remove_column :statuses, :favourites_count, :integer, default: 0, null: false
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2018_08_12_123222) do
+ActiveRecord::Schema.define(version: 2018_08_13_113448) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -456,6 +456,16 @@ ActiveRecord::Schema.define(version: 2018_08_12_123222) do
     t.index ["account_id", "status_id"], name: "index_status_pins_on_account_id_and_status_id", unique: true
   end
 
+  create_table "status_stats", force: :cascade do |t|
+    t.bigint "status_id", null: false
+    t.bigint "replies_count", default: 0, null: false
+    t.bigint "reblogs_count", default: 0, null: false
+    t.bigint "favourites_count", default: 0, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["status_id"], name: "index_status_stats_on_status_id", unique: true
+  end
+
   create_table "statuses", id: :bigint, default: -> { "timestamp_id('statuses'::text)" }, force: :cascade do |t|
     t.string "uri"
     t.text "text", default: "", null: false
@@ -468,8 +478,6 @@ ActiveRecord::Schema.define(version: 2018_08_12_123222) do
     t.integer "visibility", default: 0, null: false
     t.text "spoiler_text", default: "", null: false
     t.boolean "reply", default: false, null: false
-    t.integer "favourites_count", default: 0, null: false
-    t.integer "reblogs_count", default: 0, null: false
     t.string "language"
     t.bigint "conversation_id"
     t.boolean "local"
@@ -630,6 +638,7 @@ ActiveRecord::Schema.define(version: 2018_08_12_123222) do
   add_foreign_key "session_activations", "users", name: "fk_e5fda67334", on_delete: :cascade
   add_foreign_key "status_pins", "accounts", name: "fk_d4cb435b62", on_delete: :cascade
   add_foreign_key "status_pins", "statuses", on_delete: :cascade
+  add_foreign_key "status_stats", "statuses", on_delete: :cascade
   add_foreign_key "statuses", "accounts", column: "in_reply_to_account_id", name: "fk_c7fa917661", on_delete: :nullify
   add_foreign_key "statuses", "accounts", name: "fk_9bda1543f7", on_delete: :cascade
   add_foreign_key "statuses", "statuses", column: "in_reply_to_id", on_delete: :nullify