diff --git a/db/migrate/20230623160831_add_index_to_parent_dossier_id.rb b/db/migrate/20230623160831_add_index_to_parent_dossier_id.rb
new file mode 100644
index 000000000..4610a9461
--- /dev/null
+++ b/db/migrate/20230623160831_add_index_to_parent_dossier_id.rb
@@ -0,0 +1,7 @@
+class AddIndexToParentDossierId < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def change
+    add_index :dossiers, :parent_dossier_id, algorithm: :concurrently
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index b3d1e30c2..a387e005c 100644
--- a/db/schema.rb
+++ b/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_06_21_161733) do
+ActiveRecord::Schema[7.0].define(version: 2023_06_23_160831) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pgcrypto"
   enable_extension "plpgsql"
@@ -416,6 +416,7 @@ ActiveRecord::Schema[7.0].define(version: 2023_06_21_161733) do
     t.index ["editing_fork_origin_id"], name: "index_dossiers_on_editing_fork_origin_id"
     t.index ["groupe_instructeur_id"], name: "index_dossiers_on_groupe_instructeur_id"
     t.index ["hidden_at"], name: "index_dossiers_on_hidden_at"
+    t.index ["parent_dossier_id"], name: "index_dossiers_on_parent_dossier_id"
     t.index ["prefill_token"], name: "index_dossiers_on_prefill_token", unique: true
     t.index ["revision_id"], name: "index_dossiers_on_revision_id"
     t.index ["state"], name: "index_dossiers_on_state"