diff --git a/src/management.ml b/src/management.ml
index 6978ff93..bc85d360 100644
--- a/src/management.ml
+++ b/src/management.ml
@@ -27,14 +27,12 @@ let mk_future_denom denom_key_signf
     let open Binary_formats in
     let h_denom_pub = h_pub in
     let h_section_name = Cstring_hash_64.hash section_name in
-    let anchor_time =
-      TimeAbsoluteNBO.{ v= Util.ptime_to_int64_us stamp_start }
-    in
+    let anchor_time = TimeAbsoluteNBO.{ v= Util.ptime_to_int64 stamp_start } in
     let duration_withdraw =
       let v =
         Ptime.diff stamp_start stamp_expire_withdraw
         |> Util.ptime_of_span_exn
-        |> Util.ptime_to_int64_us
+        |> Util.ptime_to_int64
       in
       TimeRelativeNBO.{ v }
     in
@@ -66,14 +64,12 @@ let mk_future_signkey signkey_signf
   let signkey_secmod_sig =
     let open Binary_formats in
     let exchange_pub = pub in
-    let anchor_time =
-      TimeAbsoluteNBO.{ v= Util.ptime_to_int64_us stamp_start }
-    in
+    let anchor_time = TimeAbsoluteNBO.{ v= Util.ptime_to_int64 stamp_start } in
     let duration =
       let v =
         Ptime.diff stamp_start stamp_expire
         |> Util.ptime_of_span_exn
-        |> Util.ptime_to_int64_us
+        |> Util.ptime_to_int64
       in
       TimeRelativeNBO.{ v }
     in
diff --git a/src/pg.ml b/src/pg.ml
new file mode 100644
index 00000000..6deccf9b
--- /dev/null
+++ b/src/pg.ml
@@ -0,0 +1,46 @@
+(* TODO be sure to not use postgres ptime
+   add a dune stanza like for prelude:
+   "(flags (:standard -open Prelude))" *)
+module Caqti_type = struct
+  include Caqti_type
+
+  (* we want to use int64 timestamps,
+     not postgresql built-in timestamp type *)
+  let ptime : Ptime.t Caqti_type.t =
+    let encode i = Ok (Util.ptime_to_int64 i) in
+    let decode = Util.ptime_of_int64 in
+    Caqti_type.custom ~encode ~decode Caqti_type.(int64)
+end
+
+let pg_amount : Amount.t Caqti_type.t =
+  let open Amount in
+  (* TODO bad int32 conversion *)
+  Caqti_type.custom
+    ~encode:(fun amount -> Ok (amount.value, Int64.to_int32 amount.fraction))
+    ~decode:(fun (value, fraction) ->
+      let fraction = Int64.of_int32 fraction in
+      Ok { sign= None; currency= `Eur; value; fraction })
+    Caqti_type.(t2 int64 int32)
+
+(* WIP: minimum db functions for basic /management *)
+
+let pg_todo () = assert false
+
+(* signkey *)
+let activate_signing_key = pg_todo
+let lookup_signing_key = pg_todo
+let iterate_active_signkeys = pg_todo
+let insert_signkey_revocation = pg_todo
+let lookup_signkey_revocation = pg_todo
+
+(* denominations *)
+let insert_denomination_info = pg_todo
+let get_denomination_info = pg_todo
+let get_denomination_by_serial = pg_todo
+let iterate_denomination_info = pg_todo
+let iterate_denominations = pg_todo
+let get_coin_denomination = pg_todo
+let insert_denomination_revocation = pg_todo
+let get_denomination_revocation = pg_todo
+let lookup_denomination_key = pg_todo
+let add_denomination_key = pg_todo
diff --git a/src/util.ml b/src/util.ml
index 36619bb6..608f3ed5 100644
--- a/src/util.ml
+++ b/src/util.ml
@@ -9,7 +9,12 @@ end
 
 (* -- Ptime -- *)
 
-let ptime_to_int64_us p = Int64.of_float (1_000_000. *. Ptime.to_float_s p)
+let ptime_to_int64 ptime = ptime |> Ptime.to_float_s |> Int64.of_float
+
+let ptime_of_int64 i =
+  match Ptime.of_float_s (Int64.to_float i) with
+  | None -> Fmt.error "ptime_of_int64 error: `%Ld` is not a valid ptime" i
+  | Some ts -> Ok ts
 
 let ptime_of_span_exn span =
   match Ptime.of_span span with