Move sort filtering into is_usable

7 files changed, 47 insertions, 56 deletions

diff --git a/src/mango/src/mango_cursor.erl b/src/mango/src/mango_cursor.erl
index 5108d36b2..5d2ea717d 100644
--- a/src/mango/src/mango_cursor.erl
+++ b/src/mango/src/mango_cursor.erl
@@ -48,18 +48,12 @@
 create(Db, Selector0, Opts) ->
     Selector = mango_selector:normalize(Selector0),
     UsableIndexes = mango_idx:get_usable_indexes(Db, Selector, Opts),
-    case length(UsableIndexes) of
-        0 ->
-            AllDocs = mango_idx:special(Db),
-            create_cursor(Db, AllDocs, Selector, Opts);
-        _ ->
-            case mango_cursor:maybe_filter_indexes_by_ddoc(UsableIndexes, Opts) of
-                [] ->
-                    % use_index doesn't match a valid index - fall back to a valid one
-                    create_cursor(Db, UsableIndexes, Selector, Opts);
-                UserSpecifiedIndex ->
-                    create_cursor(Db, UserSpecifiedIndex, Selector, Opts)
-            end
+    case mango_cursor:maybe_filter_indexes_by_ddoc(UsableIndexes, Opts) of
+        [] ->
+            % use_index doesn't match a valid index - fall back to a valid one
+            create_cursor(Db, UsableIndexes, Selector, Opts);
+        UserSpecifiedIndex ->
+            create_cursor(Db, UserSpecifiedIndex, Selector, Opts)
     end.
 
 
diff --git a/src/mango/src/mango_idx.erl b/src/mango/src/mango_idx.erl
index 7c37585c7..211edacf4 100644
--- a/src/mango/src/mango_idx.erl
+++ b/src/mango/src/mango_idx.erl
@@ -66,13 +66,12 @@ get_usable_indexes(Db, Selector, Opts) ->
 
     SortFields = get_sort_fields(Opts),
     UsableFilter = fun(I) -> is_usable(I, Selector, SortFields) end,
-    UsableIndexes1 = lists:filter(UsableFilter, UsableIndexes0),
 
-    case maybe_filter_by_sort_fields(UsableIndexes1, Selector, SortFields) of
-        {ok, SortIndexes} -> 
-            SortIndexes;
-        {error, no_usable_index} -> 
-            ?MANGO_ERROR({no_usable_index, missing_sort_index})
+    case lists:filter(UsableFilter, UsableIndexes0) of
+        [] -> 
+            ?MANGO_ERROR({no_usable_index, missing_sort_index});
+        UsableIndexes1 -> 
+            UsableIndexes1
     end.
 
 
@@ -100,22 +99,6 @@ get_sort_fields(Opts) ->
     end.
 
 
-maybe_filter_by_sort_fields(Indexes, _Selector, []) ->
-    {ok, Indexes};
-
-maybe_filter_by_sort_fields(Indexes, Selector, SortFields) ->
-    FilterFun = fun(Idx) ->
-        Mod = idx_mod(Idx),
-        Mod:maybe_filter_by_sort_fields(Idx, SortFields, Selector)
-    end,
-    case lists:filter(FilterFun, Indexes) of
-        [] ->
-            {error, no_usable_index};
-        FilteredIndexes ->
-            {ok, FilteredIndexes}
-    end.
-
-
 new(Db, Opts) ->
     Def = get_idx_def(Opts),
     Type = get_idx_type(Opts),
diff --git a/src/mango/src/mango_idx_special.erl b/src/mango/src/mango_idx_special.erl
index a2869ad8e..aa1ec2f41 100644
--- a/src/mango/src/mango_idx_special.erl
+++ b/src/mango/src/mango_idx_special.erl
@@ -65,9 +65,11 @@ columns(#idx{def=all_docs}) ->
     [<<"_id">>].
 
 
-is_usable(#idx{def=all_docs}, Selector, _) ->
+is_usable(#idx{def=all_docs}, _Selector, []) ->
+    true;
+is_usable(#idx{def=all_docs} = Idx, Selector, SortFields) ->
     Fields = mango_idx_view:indexable_fields(Selector),
-    lists:member(<<"_id">>, Fields).
+    lists:member(<<"_id">>, Fields) and maybe_filter_by_sort_fields(Idx, SortFields, Selector).
 
 
 start_key([{'$gt', Key, _, _}]) ->
@@ -100,6 +102,13 @@ end_key([{'$eq', Key, '$eq', Key}]) ->
     Key.
 
 
+% maybe_filter_by_sort_fields(Idx, SortFields, Selector) ->
+%     Cols = columns(Idx),
+%     io:format("HERE BOOM ~p ~n ~p ~n", [Idx, Cols]),
+%     lists:prefix(SortFields, Cols).
+
+maybe_filter_by_sort_fields(_Idx, [], _Selector) ->
+    true;
 maybe_filter_by_sort_fields(Idx, SortFields, _Selector) ->
-    Cols = mango_idx:columns(Idx),
+    Cols = columns(Idx),
     lists:prefix(SortFields, Cols).
diff --git a/src/mango/src/mango_idx_text.erl b/src/mango/src/mango_idx_text.erl
index 6e4f0350b..29b4441a1 100644
--- a/src/mango/src/mango_idx_text.erl
+++ b/src/mango/src/mango_idx_text.erl
@@ -23,8 +23,7 @@
     to_json/1,
     columns/1,
     is_usable/3,
-    get_default_field_options/1,
-    maybe_filter_by_sort_fields/3
+    get_default_field_options/1
 ]).
 
 
@@ -377,16 +376,6 @@ forbid_index_all() ->
     config:get("mango", "index_all_disabled", "false").
 
 
-maybe_filter_by_sort_fields(Idx, SortFields, _Selector) ->
-    Cols = mango_idx:columns(Idx),
-    case Cols of
-        all_fields -> 
-            true;
-        _ ->
-            sets:is_subset(sets:from_list(SortFields), sets:from_list(Cols))
-    end.
-
-
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
 
diff --git a/src/mango/src/mango_idx_view.erl b/src/mango/src/mango_idx_view.erl
index fe4549e34..db3c5eb15 100644
--- a/src/mango/src/mango_idx_view.erl
+++ b/src/mango/src/mango_idx_view.erl
@@ -24,7 +24,6 @@
     columns/1,
     start_key/1,
     end_key/1,
-    maybe_filter_by_sort_fields/3,
 
     indexable_fields/1,
     field_ranges/1,
@@ -132,7 +131,8 @@ is_usable(Idx, Selector, SortFields) ->
         [<<"_id">>, <<"_rev">>]),
 
     mango_selector:has_required_fields(Selector, RequiredFields2)
-        andalso not is_text_search(Selector).
+        andalso not is_text_search(Selector)
+        andalso can_use_sort(RequiredFields, SortFields, Selector).
 
 
 is_text_search({[]}) ->
@@ -514,11 +514,12 @@ range_pos(Low, Arg, High) ->
     end.
 
 
-maybe_filter_by_sort_fields(Idx, SortFields, Selector) ->
-    Cols = mango_idx:columns(Idx),
+can_use_sort(_Cols, [], _Selector) ->
+    true;
+can_use_sort(Cols, SortFields, Selector) ->
     case lists:subtract(SortFields, Cols) of
         [] -> 
-            NormalizedSortFields = normalize_sort_fields(Cols, SortFields, Selector),
+            NormalizedSortFields = add_constant_sort_fields(Cols, SortFields, Selector),
             lists:prefix(NormalizedSortFields, Cols);
         _ ->
             false
@@ -526,7 +527,7 @@ maybe_filter_by_sort_fields(Idx, SortFields, Selector) ->
 
 
 % This is an user experience improvement. If a selector has a sort field set
-% then an index is only valid if the prefix of the sort fields match the 
+% then an index is only valid if the sort fields match the 
 % prefix of the index fields. 
 
 % e.g Index = [A, B, C] with Sort = [A, B] is a valid sort
@@ -541,7 +542,7 @@ maybe_filter_by_sort_fields(Idx, SortFields, Selector) ->
 % The sort will work as expected and this will increase the possibility
 % of the index being choosen. It also helps a user where they might not have
 % put correct initial fields in the sort.
-normalize_sort_fields(Cols, SortFields, Selector) ->
+add_constant_sort_fields(Cols, SortFields, Selector) ->
     lists:foldr(fun (Col, Sort) ->
         case lists:member(Col, SortFields) of
             true -> 
diff --git a/src/mango/test/18-json-sort.py b/src/mango/test/18-json-sort.py
index 58ace485c..6c5db4880 100644
--- a/src/mango/test/18-json-sort.py
+++ b/src/mango/test/18-json-sort.py
@@ -154,6 +154,20 @@ class JSONIndexSortOptimisations(mango.DbPerClass):
             resp = e.response.json()
             self.assertEqual(resp["error"], "no_usable_index")
 
+    def test_empty_sort(self):
+        self.db.create_index(["cars", "age", "name"], name="cars-age-name")
+        selector = {
+            "name": {
+                "$gt": "Eddie",
+            },
+            "age": 10,
+            "cars": {
+                "$gt": "1"
+            }
+        }
+        explain = self.db.find(selector, explain=True)
+        self.assertEqual(explain["index"]["name"], "cars-age-name")
+
     def test_in_between(self):
         self.db.create_index(["cars", "age", "name"], name="cars-age-name")
         selector = {
diff --git a/src/mango/test/mango.py b/src/mango/test/mango.py
index 9b6b998cd..13873211a 100644
--- a/src/mango/test/mango.py
+++ b/src/mango/test/mango.py
@@ -240,6 +240,7 @@ class Database(object):
         else:
             path = self.path("_find")
         r = self.sess.post(path, data=body)
+        print r.json()
         r.raise_for_status()
         if explain or return_raw:
             return r.json()