Extract counters from accounts table to account_stats table (#9295)

app/models/account_stat.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: account_stats
+#
+#  id              :bigint(8)        not null, primary key
+#  account_id      :bigint(8)        not null
+#  statuses_count  :bigint(8)        default(0), not null
+#  following_count :bigint(8)        default(0), not null
+#  followers_count :bigint(8)        default(0), not null
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#
+
+class AccountStat < ApplicationRecord
+  belongs_to :account, inverse_of: :account_stat
+
+  def increment_count!(key)
+    update(key => public_send(key) + 1)
+  end
+
+  def decrement_count!(key)
+    update(key => [public_send(key) - 1, 0].max)
+  end
+end