diff --git a/src/proto_alpha/lib_protocol/contract_repr.ml b/src/proto_alpha/lib_protocol/contract_repr.ml
index 1fd9d0c5d43ccceab5c24cb927979eff35435dbb..02dd7440c7e9599842a3558620910f997b7e2648 100644
--- a/src/proto_alpha/lib_protocol/contract_repr.ml
+++ b/src/proto_alpha/lib_protocol/contract_repr.ml
@@ -188,7 +188,7 @@ let rpc_arg =
     ~destruct
     ()
 
-module Index = struct
+module Index_008 = struct
   type t = contract
 
   let path_length = 7
@@ -228,3 +228,27 @@ module Index = struct
 
   let compare = compare
 end
+
+module Index = struct
+  type t = contract
+
+  let path_length = 1
+
+  let to_path c l =
+    let raw_key = Data_encoding.Binary.to_bytes_exn encoding c in
+    let (`Hex key) = Hex.of_bytes raw_key in
+    key :: l
+
+  let of_path = function
+    | [key] ->
+        let raw_key = Hex.to_bytes (`Hex key) in
+        Data_encoding.Binary.of_bytes encoding raw_key
+    | _ ->
+        None
+
+  let rpc_arg = rpc_arg
+
+  let encoding = encoding
+
+  let compare = compare
+end
diff --git a/src/proto_alpha/lib_protocol/contract_repr.mli b/src/proto_alpha/lib_protocol/contract_repr.mli
index 53935e460bbb6e57453a45d5b8593319c4d4de0c..bc49c917926a1c53b47ed0502bc4d1453f90be50 100644
--- a/src/proto_alpha/lib_protocol/contract_repr.mli
+++ b/src/proto_alpha/lib_protocol/contract_repr.mli
@@ -77,4 +77,6 @@ val origination_nonce_encoding : origination_nonce Data_encoding.t
 
 val rpc_arg : contract RPC_arg.arg
 
+module Index_008 : Storage_description.INDEX with type t = t
+
 module Index : Storage_description.INDEX with type t = t
diff --git a/src/proto_alpha/lib_protocol/init_storage.ml b/src/proto_alpha/lib_protocol/init_storage.ml
index 1c312c5f256454463a3a3a80b0beacee008d7a1a..e95f73a1ea404e163b1f318bc8cea8a34ae6aa00 100644
--- a/src/proto_alpha/lib_protocol/init_storage.ml
+++ b/src/proto_alpha/lib_protocol/init_storage.ml
@@ -24,6 +24,64 @@
 (*                                                                           *)
 (*****************************************************************************)
 
+module Migrate_from_008_to_009 = struct
+  let rec path_remove_prefix = function
+    | (h1 :: t1, h2 :: t2) when String.(equal h1 h2) ->
+        path_remove_prefix (t1, t2)
+    | ([], t2) ->
+        return t2
+    | (_, _) ->
+        (*can't happens because the path have been digged starting with that
+          prefix *)
+        assert false
+
+  let fold_keys (type t) ~index ~init ~f ~index_path ctxt =
+    let (module Index : Storage_functors.INDEX with type t = t) = index in
+    let rec dig len path acc =
+      if Compare.Int.(len <= 0) then
+        path_remove_prefix (index_path, path)
+        >>=? fun key_path ->
+        match Index.of_path key_path with
+        | None ->
+            (* can't happens as the path have been digged and can't be false *)
+            assert false
+        | Some value ->
+            f path value acc
+      else
+        Raw_context.fold ctxt path ~init:(Ok acc) ~f:(fun k acc ->
+            Lwt.return acc
+            >>=? fun acc ->
+            match k with `Dir k | `Key k -> dig (len - 1) k acc)
+    in
+    dig Index.path_length index_path init
+
+  let migrate_indexed_storage (type t) ctxt ~from_index ~to_index ~index_path =
+    let (module To_index : Storage_functors.INDEX with type t = t) =
+      to_index
+    in
+    let tmp_index_path =
+      let rev_path = List.rev index_path in
+      List.rev (("tmp_" ^ List.hd rev_path) :: List.tl rev_path)
+    in
+    fold_keys
+      ~index:from_index
+      ~init:(ctxt, false)
+      ~f:(fun old_path value (ctxt, _has_value) ->
+        let new_path = tmp_index_path @ To_index.to_path value [] in
+        Raw_context.copy ctxt ~from:old_path ~to_:new_path
+        >>=? fun ctxt -> return (ctxt, true))
+      ~index_path
+      ctxt
+    >>=? fun (ctxt, has_value) ->
+    if has_value then
+      Raw_context.remove_rec ctxt index_path
+      >>= fun ctxt ->
+      Raw_context.copy ctxt tmp_index_path index_path
+      >>=? fun ctxt ->
+      Raw_context.remove_rec ctxt tmp_index_path >>= fun ctxt -> return ctxt
+    else return ctxt
+end
+
 (* This is the genesis protocol: initialise the state *)
 let prepare_first_block ctxt ~typecheck ~level ~timestamp ~fitness =
   Raw_context.prepare_first_block ~level ~timestamp ~fitness ctxt
@@ -61,6 +119,94 @@ let prepare_first_block ctxt ~typecheck ~level ~timestamp ~fitness =
       *)
       let balance_updates = [] in
       Storage.Pending_migration_balance_updates.init ctxt balance_updates
+      >>=? fun ctxt ->
+      let contract_index_008 =
+        ( module Storage.Make_index (Contract_repr.Index_008)
+        : Storage_functors.INDEX
+          with type t = Contract_repr.t )
+      in
+      let contract_index =
+        ( module Storage.Make_index (Contract_repr.Index)
+        : Storage_functors.INDEX
+          with type t = Contract_repr.t )
+      in
+      Migrate_from_008_to_009.migrate_indexed_storage
+        ctxt
+        ~from_index:contract_index_008
+        ~to_index:contract_index
+        ~index_path:["contracts"; "index"]
+      >>=? fun ctxt ->
+      Storage.Contract.fold
+        ~init:(ok ctxt)
+        ~f:(fun contract ctxt ->
+          Lwt.return ctxt
+          >>=? fun ctxt ->
+          Migrate_from_008_to_009.migrate_indexed_storage
+            ~from_index:contract_index_008
+            ~to_index:contract_index
+            ~index_path:
+              ( ["contracts"; "index"]
+              @ Contract_repr.Index.to_path contract []
+              @ ["delegated"] )
+            ctxt)
+        ctxt
+      >>=? fun ctxt ->
+      let bigmap_index_008 =
+        ( module Storage.Make_index (Storage.Big_map.Index_008)
+        : Storage_functors.INDEX
+          with type t = Storage.Big_map.id )
+      in
+      let bigmap_index =
+        ( module Storage.Make_index (Storage.Big_map.Index)
+        : Storage_functors.INDEX
+          with type t = Storage.Big_map.id )
+      in
+      Migrate_from_008_to_009.migrate_indexed_storage
+        ctxt
+        ~from_index:bigmap_index_008
+        ~to_index:bigmap_index
+        ~index_path:["big_maps"; "index"]
+      >>=? fun ctxt ->
+      let rolls_index_008 =
+        ( module Storage.Make_index (Roll_repr.Index_008)
+        : Storage_functors.INDEX
+          with type t = Roll_repr.t )
+      in
+      let rolls_index =
+        (module Storage.Make_index (Roll_repr.Index) : Storage_functors.INDEX
+          with type t = Roll_repr.t )
+      in
+      let snapshot_rolls_index_008 =
+        let (module Rolls_index_008) = rolls_index_008 in
+        ( module Storage_functors.Pair
+                   (Storage.Roll.Snapshoted_owner_index)
+                   (Rolls_index_008) : Storage_functors.INDEX
+          with type t = (Cycle_repr.t * int) * Roll_repr.t )
+      in
+      let snapshot_rolls_index =
+        let (module Rolls_index) = rolls_index in
+        ( module Storage_functors.Pair
+                   (Storage.Roll.Snapshoted_owner_index)
+                   (Rolls_index) : Storage_functors.INDEX
+          with type t = (Cycle_repr.t * int) * Roll_repr.t )
+      in
+      Migrate_from_008_to_009.migrate_indexed_storage
+        ctxt
+        ~from_index:rolls_index_008
+        ~to_index:rolls_index
+        ~index_path:["rolls"; "index"]
+      >>=? fun ctxt ->
+      Migrate_from_008_to_009.migrate_indexed_storage
+        ctxt
+        ~from_index:snapshot_rolls_index_008
+        ~to_index:snapshot_rolls_index
+        ~index_path:["rolls"; "owner"; "snapshot"]
+      >>=? fun ctxt ->
+      Migrate_from_008_to_009.migrate_indexed_storage
+        ctxt
+        ~from_index:rolls_index_008
+        ~to_index:rolls_index
+        ~index_path:["rolls"; "owner"; "current"]
 
 let prepare ctxt ~level ~predecessor_timestamp ~timestamp ~fitness =
   Raw_context.prepare ~level ~predecessor_timestamp ~timestamp ~fitness ctxt
diff --git a/src/proto_alpha/lib_protocol/roll_repr.ml b/src/proto_alpha/lib_protocol/roll_repr.ml
index 74b47360b2ace54d0ad6efac2f2fdcd620a3ba57..5af663463bc30cc9aa90dc8e5e865462e3722a81 100644
--- a/src/proto_alpha/lib_protocol/roll_repr.ml
+++ b/src/proto_alpha/lib_protocol/roll_repr.ml
@@ -39,7 +39,7 @@ let rpc_arg = RPC_arg.like RPC_arg.int32 "roll"
 
 let to_int32 v = v
 
-module Index = struct
+module Index_008 = struct
   type t = roll
 
   let path_length = 3
@@ -63,3 +63,19 @@ module Index = struct
 
   let compare = compare
 end
+
+module Index = struct
+  type t = roll
+
+  let path_length = 1
+
+  let to_path roll l = Int32.to_string roll :: l
+
+  let of_path = function s :: _ -> Int32.of_string_opt s | _ -> None
+
+  let rpc_arg = rpc_arg
+
+  let encoding = encoding
+
+  let compare = compare
+end
diff --git a/src/proto_alpha/lib_protocol/roll_repr.mli b/src/proto_alpha/lib_protocol/roll_repr.mli
index cb792b0128e73203abec091ee1aadf019aa356a1..c3ddd19cf617ab0a74683d1f2e585c5586fa7141 100644
--- a/src/proto_alpha/lib_protocol/roll_repr.mli
+++ b/src/proto_alpha/lib_protocol/roll_repr.mli
@@ -41,4 +41,6 @@ val to_int32 : roll -> Int32.t
 
 val ( = ) : roll -> roll -> bool
 
+module Index_008 : Storage_description.INDEX with type t = roll
+
 module Index : Storage_description.INDEX with type t = roll
diff --git a/src/proto_alpha/lib_protocol/storage.ml b/src/proto_alpha/lib_protocol/storage.ml
index cf1d39cabde90b5e5f1b62b98a49136724eef42b..8199f09f158fe389a896d68e4f0bbc50984c9420 100644
--- a/src/proto_alpha/lib_protocol/storage.ml
+++ b/src/proto_alpha/lib_protocol/storage.ml
@@ -337,9 +337,9 @@ module Big_map = struct
     let init ctxt = init ctxt Lazy_storage_kind.Big_map.Id.init
   end
 
-  module Index = struct
-    (* After flat storage, just use module Index = Lazy_storage_kind.Big_map.Id *)
+  module Index = Lazy_storage_kind.Big_map.Id
 
+  module Index_008 = struct
     include Lazy_storage_kind.Big_map.Id
 
     let path_length = 6 + path_length
diff --git a/src/proto_alpha/lib_protocol/storage.mli b/src/proto_alpha/lib_protocol/storage.mli
index 4ec426976050805080486bd31c59e8c60e024645..28866035fff04052c7d7bbcb544d3b3034d4508c 100644
--- a/src/proto_alpha/lib_protocol/storage.mli
+++ b/src/proto_alpha/lib_protocol/storage.mli
@@ -44,10 +44,27 @@ module Block_priority : sig
   val init : Raw_context.t -> int -> Raw_context.t tzresult Lwt.t
 end
 
+module Make_index (H : Storage_description.INDEX) : sig
+  type t = H.t
+
+  val path_length : int
+
+  val to_path : t -> string list -> string list
+
+  val of_path : string list -> t option
+
+  type 'a ipath = 'a * t
+
+  val args : ('a, t, 'a ipath) Storage_description.args
+end
+
 module Roll : sig
   (** Storage from this submodule must only be accessed through the
       module `Roll`. *)
 
+  module Snapshoted_owner_index :
+    Storage_functors.INDEX with type t = Cycle_repr.t * int
+
   module Owner :
     Indexed_data_snapshotable_storage
       with type key = Roll_repr.t
@@ -223,6 +240,10 @@ end
 module Big_map : sig
   type id = Lazy_storage_kind.Big_map.Id.t
 
+  module Index_008 : Storage_description.INDEX with type t = id
+
+  module Index : Storage_description.INDEX with type t = id
+
   module Next : sig
     val incr : Raw_context.t -> (Raw_context.t * id) tzresult Lwt.t
 
diff --git a/tezt/_regressions/rpc/alpha.delegates.out b/tezt/_regressions/rpc/alpha.delegates.out
index 9488b536100bf71b25262a775e201f96b97073c3..ba15ba124239331145209af693faecc92bab54a5 100644
--- a/tezt/_regressions/rpc/alpha.delegates.out
+++ b/tezt/_regressions/rpc/alpha.delegates.out
@@ -37,13 +37,13 @@ false
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]'
 Fatal error:
   Command failed : Storage error:
-                     Missing key 'contracts/index/63/cb/4c/cb/6c/4c/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/balance'.
+                     Missing key 'contracts/index/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/balance'.
   
 
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]/balance'
 Fatal error:
   Command failed : Storage error:
-                     Missing key 'contracts/index/63/cb/4c/cb/6c/4c/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/balance'.
+                     Missing key 'contracts/index/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/balance'.
   
 
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]/deactivated'
@@ -52,7 +52,7 @@ false
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]/delegated_balance'
 Fatal error:
   Command failed : Storage error:
-                     Missing key 'contracts/index/63/cb/4c/cb/6c/4c/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/balance'.
+                     Missing key 'contracts/index/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/balance'.
   
 
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]/delegated_contracts'
@@ -67,7 +67,7 @@ Fatal error:
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]/grace_period'
 Fatal error:
   Command failed : Storage error:
-                     Missing key 'contracts/index/63/cb/4c/cb/6c/4c/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/delegate_desactivation'.
+                     Missing key 'contracts/index/0000b443c2c85e0aeb6a4c0a37783f4d8251a956e8ad/delegate_desactivation'.
   
 
 ./tezos-client rpc get '/chains/main/blocks/head/context/delegates/[PUBLIC_KEY_HASH]/staking_balance'