diff --git a/db/migrate/20200820174703_add_partial_target_id_index_to_reviewables.rb b/db/migrate/20200820174703_add_partial_target_id_index_to_reviewables.rb
new file mode 100644
index 00000000000..55d2bd81ac6
--- /dev/null
+++ b/db/migrate/20200820174703_add_partial_target_id_index_to_reviewables.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AddPartialTargetIdIndexToReviewables < ActiveRecord::Migration[6.0]
+  disable_ddl_transaction!
+
+  def change
+    add_index :reviewables, [:target_id], where: "target_type = 'Post'", algorithm: :concurrently, name: "index_reviewables_on_target_id_where_post_type_eq_post"
+  end
+end