1 files changed, 54 insertions, 1 deletions

diff --git a/lib/analysers/query.ml b/lib/analysers/query.ml
index dff3b9d..bcf4a72 100644
--- a/lib/analysers/query.ml
+++ b/lib/analysers/query.ml
@@ -273,6 +273,49 @@ type query = {
   parameters : ImportCSV.DataType.t Seq.t;
 }
 
+let rec take_elements :
+    prefix:'a list -> eq:('a -> 'a -> bool) -> 'a list -> 'a list =
+ fun ~prefix ~eq group ->
+  match (prefix, group) with
+  | [], any -> any
+  | _, [] -> []
+  | hd1 :: tl1, hd2 :: tl2 when eq hd1 hd2 -> take_elements ~eq ~prefix:tl1 tl2
+  | _, _ -> raise Not_found
+
+(** The window functions shall be grouped in the same way as the uniq property.
+    (We cannot make a partition over a group not kept in the final result).
+
+    But the SQL query need to remove from the window function the elements
+    already defined in the group by statement, and we need to filter them from
+    the configuration before building the query. *)
+let clean_window :
+    prefix:Path.t ImportExpression.T.t list ->
+    Path.t ImportExpression.T.t ->
+    Path.t ImportExpression.T.t =
+ fun ~prefix expression ->
+  let open ImportExpression.T in
+  let rec f = function
+    | Expr e -> Expr (f e)
+    | Empty -> Empty
+    | Literal s -> Literal s
+    | Integer i -> Integer i
+    | Path p -> Path p
+    | Concat pp -> Concat (List.map ~f pp)
+    | Function' (name, pp) -> Function' (name, List.map ~f pp)
+    | Function (name, pp) -> Function (name, List.map ~f pp)
+    | Nvl pp -> Nvl (List.map ~f pp)
+    | Join (sep, pp) -> Join (sep, List.map ~f pp)
+    | Window (window_f, group, order) ->
+        let w = map_window ~f window_f in
+        let group =
+          take_elements ~eq:(ImportExpression.T.equal Path.equal) ~prefix group
+        in
+        Window (w, List.map ~f group, List.map ~f order)
+    | BOperator (n, arg1, arg2) -> BOperator (n, f arg1, f arg2)
+    | GEquality (n, arg1, args) -> GEquality (n, f arg1, List.map ~f args)
+  in
+  f expression
+
 (** Build the query and return also the mapping in order to identify each
     external links between files.
 
@@ -301,7 +344,17 @@ let select : Syntax.t -> query * Path.t ImportExpression.T.t array =
   *)
   let headers = Array.make (List.length conf.columns) (Obj.magic None) in
 
-  let columns = List.to_seq conf.columns |> Seq.mapi (fun i c -> (i, c)) in
+  (* Transform the columns to extract from the query. 
+      - Associate each of them with a number
+      - Clean the window functions and remove the part already defined in the
+        [uniq] parameter.
+   *)
+  let columns =
+    List.to_seq conf.columns
+    |> Seq.mapi (fun i c ->
+           let expression = c in
+           (i, clean_window ~prefix:conf.uniq expression))
+  in
   let formatter = Format.formatter_of_buffer b in
   let () =
     Format.fprintf formatter "SELECT %a"