Revert "Fix incorrect index selection when sort specified (apache#866)"

This reverts commit d0445f5.

src/mango/src/mango_cursor.erl

@@ -46,7 +46,7 @@
 
 create(Db, Selector0, Opts) ->
     Selector = mango_selector:normalize(Selector0),
-    UsableIndexes = mango_idx:get_usable_indexes(Db, Selector, Opts),
+    UsableIndexes = mango_idx:get_usable_indexes(Db, Selector0, Opts),
 
     {use_index, IndexSpecified} = proplists:lookup(use_index, Opts),
     case {length(UsableIndexes), length(IndexSpecified)} of

src/mango/src/mango_error.erl

@@ -43,7 +43,7 @@ info(mango_cursor, {no_usable_index, selector_unsupported}) ->
     {
         400,
         <<"no_usable_index">>,
-        <<"The index specified with \"use_index\" is not usable for the query.">>
+        <<"There is no index available for this selector.">>
     };
 
 info(mango_json_bookmark, {invalid_bookmark, BadBookmark}) ->

src/mango/src/mango_idx.erl

@@ -20,6 +20,7 @@
 -export([
     list/1,
     recover/1,
+    for_sort/2,
 
     new/2,
     validate_new/2,
@@ -35,7 +36,7 @@
     def/1,
     opts/1,
     columns/1,
-    is_usable/3,
+    is_usable/2,
     start_key/2,
     end_key/2,
     cursor_mod/1,
@@ -56,8 +57,9 @@ list(Db) ->
     {ok, Indexes} = ddoc_cache:open(db_to_name(Db), ?MODULE),
     Indexes.
 
+get_usable_indexes(Db, Selector0, Opts) ->
+    Selector = mango_selector:normalize(Selector0),
 
-get_usable_indexes(Db, Selector, Opts) ->
     ExistingIndexes = mango_idx:list(Db),
     if ExistingIndexes /= [] -> ok; true ->
         ?MANGO_ERROR({no_usable_index, no_indexes_defined})
@@ -68,17 +70,13 @@ get_usable_indexes(Db, Selector, Opts) ->
         ?MANGO_ERROR({no_usable_index, no_index_matching_name})
     end,
 
-    SortFields = get_sort_fields(Opts),
-    UsableFilter = fun(I) -> is_usable(I, Selector, SortFields) end,
-    UsableIndexes0 = lists:filter(UsableFilter, FilteredIndexes),
-
-    case maybe_filter_by_sort_fields(UsableIndexes0, SortFields) of
-        {ok, SortIndexes} -> 
-            SortIndexes;
-        {error, no_usable_index} -> 
-            ?MANGO_ERROR({no_usable_index, missing_sort_index})
-    end.
+    SortIndexes = mango_idx:for_sort(FilteredIndexes, Opts),
+    if SortIndexes /= [] -> ok; true ->
+        ?MANGO_ERROR({no_usable_index, missing_sort_index})
+    end,
 
+    UsableFilter = fun(I) -> mango_idx:is_usable(I, Selector) end,
+    lists:filter(UsableFilter, SortIndexes).
 
 recover(Db) ->
     {ok, DDocs0} = mango_util:open_ddocs(Db),
@@ -95,38 +93,33 @@ recover(Db) ->
     end, DDocs)}.
 
 
-get_sort_fields(Opts) ->
+for_sort(Indexes, Opts) ->
+    % If a sort was specified we have to find an index that
+    % can satisfy the request.
     case lists:keyfind(sort, 1, Opts) of
-        {sort, Sort} ->
-            mango_sort:fields(Sort);
+        {sort, {SProps}} when is_list(SProps) ->
+            for_sort_int(Indexes, {SProps});
         _ ->
-            []
+            Indexes
     end.
 
 
-maybe_filter_by_sort_fields(Indexes, []) ->
-    {ok, Indexes};
-
-maybe_filter_by_sort_fields(Indexes, SortFields) ->
+for_sort_int(Indexes, Sort) ->
+    Fields = mango_sort:fields(Sort),
     FilterFun = fun(Idx) ->
         Cols = mango_idx:columns(Idx),
         case {mango_idx:type(Idx), Cols} of
             {_, all_fields} ->
                 true;
             {<<"text">>, _} ->
-                sets:is_subset(sets:from_list(SortFields), sets:from_list(Cols));
+                sets:is_subset(sets:from_list(Fields), sets:from_list(Cols));
             {<<"json">>, _} ->
-                lists:prefix(SortFields, Cols);
+                lists:prefix(Fields, Cols);
             {<<"special">>, _} ->
-                lists:prefix(SortFields, Cols)
+                lists:prefix(Fields, Cols)
         end
     end,
-    case lists:filter(FilterFun, Indexes) of
-        [] ->
-            {error, no_usable_index};
-        FilteredIndexes ->
-            {ok, FilteredIndexes}
-    end.
+    lists:filter(FilterFun, Indexes).
 
 
 new(Db, Opts) ->
@@ -257,9 +250,9 @@ columns(#idx{}=Idx) ->
     Mod:columns(Idx).
 
 
-is_usable(#idx{}=Idx, Selector, SortFields) ->
+is_usable(#idx{}=Idx, Selector) ->
     Mod = idx_mod(Idx),
-    Mod:is_usable(Idx, Selector, SortFields).
+    Mod:is_usable(Idx, Selector).
 
 
 start_key(#idx{}=Idx, Ranges) ->

src/mango/src/mango_idx_special.erl

@@ -20,7 +20,7 @@
     from_ddoc/1,
     to_json/1,
     columns/1,
-    is_usable/3,
+    is_usable/2,
     start_key/1,
     end_key/1
 ]).
@@ -63,7 +63,7 @@ columns(#idx{def=all_docs}) ->
     [<<"_id">>].
 
 
-is_usable(#idx{def=all_docs}, Selector, _) ->
+is_usable(#idx{def=all_docs}, Selector) ->
     Fields = mango_idx_view:indexable_fields(Selector),
     lists:member(<<"_id">>, Fields).
 

src/mango/src/mango_idx_text.erl

@@ -22,7 +22,7 @@
     from_ddoc/1,
     to_json/1,
     columns/1,
-    is_usable/3,
+    is_usable/2,
     get_default_field_options/1
 ]).
 
@@ -125,7 +125,7 @@ columns(Idx) ->
     end.
 
 
-is_usable(Idx, Selector, _) ->
+is_usable(Idx, Selector) ->
     case columns(Idx) of
         all_fields ->
             true;

src/mango/src/mango_idx_view.erl

@@ -20,7 +20,7 @@
     remove/2,
     from_ddoc/1,
     to_json/1,
-    is_usable/3,
+    is_usable/2,
     columns/1,
     start_key/1,
     end_key/1,
@@ -114,17 +114,12 @@ columns(Idx) ->
     [Key || {Key, _} <- Fields].
 
 
-is_usable(Idx, Selector, SortFields) ->
-    % This index is usable if all of the columns are
+is_usable(Idx, Selector) ->
+    % This index is usable if all of the columns are 
     % restricted by the selector such that they are required to exist
     % and the selector is not a text search (so requires a text index)
     RequiredFields = columns(Idx),
-
-    % sort fields are required to exist in the results so 
-    % we don't need to check the selector for these
-    RequiredFields1 = ordsets:subtract(lists:usort(RequiredFields), lists:usort(SortFields)),
-
-    mango_selector:has_required_fields(Selector, RequiredFields1)
+    mango_selector:has_required_fields(Selector, RequiredFields)
         andalso not is_text_search(Selector).
 
 

src/mango/src/mango_selector.erl

@@ -609,7 +609,7 @@ has_required_fields([{[{Field, Cond}]} | Rest], RequiredFields) ->
         _ ->
             has_required_fields(Rest, lists:delete(Field, RequiredFields))
     end.
-
+    
 
 %%%%%%%% module tests below %%%%%%%%
 

src/mango/test/02-basic-find-test.py

@@ -222,52 +222,6 @@ def test_sort(self):
         docs2 = list(reversed(sorted(docs1, key=lambda d: d["age"])))
         assert docs1 is not docs2 and docs1 == docs2
 
-    def test_sort_desc_complex(self):
-        docs = self.db.find({
-            "company": {"$lt": "M"},
-            "$or": [
-                {"company": "Dreamia"},
-                {"manager": True}
-            ]
-        }, sort=[{"company":"desc"}, {"manager":"desc"}])
-
-        companies_returned = list(d["company"] for d in docs)
-        desc_companies = sorted(companies_returned, reverse=True)
-        self.assertEqual(desc_companies, companies_returned)
-
-    def test_sort_with_primary_sort_not_in_selector(self):
-        try:
-            docs = self.db.find({
-                "name.last": {"$lt": "M"}
-            }, sort=[{"name.first":"desc"}])    
-        except Exception as e:
-            self.assertEqual(e.response.status_code, 400)
-            resp = e.response.json()
-            self.assertEqual(resp["error"], "no_usable_index")
-        else:
-            raise AssertionError("expected find error")
-
-    def test_sort_exists_true(self):
-        docs1 = self.db.find({"age": {"$gt": 0, "$exists": True}}, sort=[{"age":"asc"}])
-        docs2 = list(sorted(docs1, key=lambda d: d["age"]))
-        assert docs1 is not docs2 and docs1 == docs2
-
-    def test_sort_desc_complex_error(self):
-        try:
-            self.db.find({
-            "company": {"$lt": "M"},
-            "$or": [
-                {"company": "Dreamia"},
-                {"manager": True}
-            ]
-        }, sort=[{"company":"desc"}])
-        except Exception as e:
-            self.assertEqual(e.response.status_code, 400)
-            resp = e.response.json()
-            self.assertEqual(resp["error"], "no_usable_index")
-        else:
-            raise AssertionError("expected find error")
-
     def test_fields(self):
         selector = {"age": {"$gt": 0}}
         docs = self.db.find(selector, fields=["user_id", "location.address"])