Remove duplicate reactions

db/migrate/20231220100445_remove_duplicate_reactions.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class RemoveDuplicateReactions < ActiveRecord::Migration[7.0]
+  def up
+    execute <<~SQUIRREL
+      DELETE FROM reactions
+      WHERE id IN (
+        SELECT id FROM (
+            SELECT id, row_number() over (PARTITION BY parent_type, parent_id, user_id ORDER BY id) AS row_number FROM reactions
+        )s WHERE row_number >= 2
+      )
+    SQUIRREL
+
+    add_index :reactions, %i[parent_type parent_id user_id], unique: true
+  end
+
+  def down
+    remove_index :reactions, %i[parent_type parent_id user_id]
+  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[7.0].define(version: 2023_12_09_212629) do
+ActiveRecord::Schema[7.0].define(version: 2023_12_20_100445) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -149,6 +149,7 @@ ActiveRecord::Schema[7.0].define(version: 2023_12_09_212629) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["parent_id", "parent_type"], name: "index_reactions_on_parent_id_and_parent_type"
+    t.index ["parent_type", "parent_id", "user_id"], name: "index_reactions_on_parent_type_and_parent_id_and_user_id", unique: true
     t.index ["user_id", "created_at"], name: "index_reactions_on_user_id_and_created_at"
   end