diff --git a/db/migrate/20240503131630_add_unique_constraint_to_view_states.rb b/db/migrate/20240503131630_add_unique_constraint_to_view_states.rb
new file mode 100644
index 000000000..c00a21fe7
--- /dev/null
+++ b/db/migrate/20240503131630_add_unique_constraint_to_view_states.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class AddUniqueConstraintToViewStates < ActiveRecord::Migration[7.0]
+  def up
+    # delete the duplicates
+    execute 'WITH uniq AS
+      (SELECT DISTINCT ON (user_id, viewable_id, viewable_type) * FROM view_states)
+      DELETE FROM view_states WHERE view_states.id NOT IN
+        (SELECT id FROM uniq)'
+
+    # add index
+    add_index :view_states, %i(user_id viewable_id viewable_type), unique: true
+  end
+
+  def down
+    remove_index :view_states, columns: %i(user_id viewable_id viewable_type)
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 758512996..4c04d2527 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -1294,6 +1294,7 @@ ActiveRecord::Schema[7.0].define(version: 2024_01_18_094253) do
     t.bigint "viewable_id"
     t.datetime "created_at", precision: nil, null: false
     t.datetime "updated_at", precision: nil, null: false
+    t.index ["user_id", "viewable_id", "viewable_type"], name: "index_view_states_on_user_id_and_viewable_id_and_viewable_type", unique: true
     t.index ["user_id"], name: "index_view_states_on_user_id"
     t.index ["viewable_type", "viewable_id"], name: "index_view_states_on_viewable_type_and_viewable_id"
   end