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

app/models/follow.rb

@@ -16,11 +16,8 @@ class Follow < ApplicationRecord
   include Paginable
   include RelationshipCacheable
 
-  belongs_to :account, counter_cache: :following_count
-
-  belongs_to :target_account,
-             class_name: 'Account',
-             counter_cache: :followers_count
+  belongs_to :account
+  belongs_to :target_account, class_name: 'Account'
 
   has_one :notification, as: :activity, dependent: :destroy
 
@@ -39,7 +36,9 @@ class Follow < ApplicationRecord
   end
 
   before_validation :set_uri, only: :create
+  after_create :increment_cache_counters
   after_destroy :remove_endorsements
+  after_destroy :decrement_cache_counters
 
   private
 
@@ -50,4 +49,14 @@ class Follow < ApplicationRecord
   def remove_endorsements
     AccountPin.where(target_account_id: target_account_id, account_id: account_id).delete_all
   end
+
+  def increment_cache_counters
+    account&.increment_count!(:following_count)
+    target_account&.increment_count!(:followers_count)
+  end
+
+  def decrement_cache_counters
+    account&.decrement_count!(:following_count)
+    target_account&.decrement_count!(:followers_count)
+  end
 end