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-rw-r--r--lib/nt.ml7
1 files changed, 7 insertions, 0 deletions
diff --git a/lib/nt.ml b/lib/nt.ml
index 3882288..41de1d0 100644
--- a/lib/nt.ml
+++ b/lib/nt.ml
@@ -33,6 +33,7 @@ type plan_node =
concrete join algorithm (e.g. HashJoin, NestedLoop, LeapFrog, &c) *)
| Join of { left : plan_node; right : plan_node; on_attrs : string list }
| Take of { limit : int; source : plan_node }
+ | Project of { source : plan_node; attrs : string list }
module Error = struct
open Condition
@@ -326,6 +327,12 @@ module Make (B : Backend) = struct
(match Nt_ffi.ptr_to_opt raw with
| None -> Error (Error.cursor_error "plan_take failed")
| Some p -> Ok p)
+ | Project { source; attrs } ->
+ Nt_ffi.with_strings_as_char_array attrs (fun attrs ->
+ let* sp = build_plan source in
+ let raw = Nt_ffi.rnt_plan_project (Nt_ffi.nint_to_ptr sp) attrs in
+ Nt_ffi.ptr_to_opt raw
+ |> Option.to_result ~none:(Error.cursor_error "plan_project failed"))
let execute_query (plan : plan_node) ~(rel_name : string) :
(tuple_stream, Condition.t) result =