Allow multiple jq expressions in index definitions

If have a document like:

    {
      "foo": "a b",
      "bar": "x y"
    }

And an index definition like:

    [
      { "foo_words": { "$jq": '.foo | split(" ") | .[]' } },
      { "bar_words": { "$jq": '.bar | split(" ") | .[]' } }
    ]

Then this should produce four index keys for the document:

    ("a", "x")
    ("a", "y")
    ("b", "x")
    ("b", "y")

This lets us query on multiple virtual fields in a single query. The
implementation here allows jq expressions (that return multiple values)
to be mixed with normal field access that returns a single value;
`flatten_keys/1` returns the product of any multi-valued index fields.
For example, above `foo_words` produces values `["a", "b"]` and
`bar_words` produces `["x", "y"]`, and we multiply this out giving the
four keys above.

src/mango/src/mango_cursor_view.erl

@@ -236,6 +236,8 @@ choose_best_index(_DbName, IndexRanges) ->
  {SelectedIndex, SelectedIndexRanges, _} = hd(lists:sort(Cmp, IndexRanges)),
  {SelectedIndex, SelectedIndexRanges}.
 
+add_virtual_field({Props}, {[{<<"$and">>, [{[{K1, _}]}, {[{K2, _}]}]}]}, [V1, V2]) ->
+ {lists:append(Props, [{K1, V1}, {K2, V2}])};
 add_virtual_field({Props}, {[{Key, _}]}, [Value]) ->
  {lists:append(Props, [{Key, Value}])};
 add_virtual_field(Props, _, _) ->
@@ -265,7 +267,7 @@ view_cb({row, Row}, #mrargs{extra = Options} = Acc) ->
  put(mango_docs_examined, get(mango_docs_examined) + 1),
  Selector = couch_util:get_value(selector, Options),
  couch_stats:increment_counter([mango, docs_examined]),
- io:format("----[view_cb selector] ~p~n", [Selector]),
+ io:format("----[view_cb selector] doc = ~p :: selector = ~p :: key = ~p~n", [Doc, Selector, Key]),
  Doc1 = add_virtual_field(Doc, Selector, Key),
  case mango_selector:match(Selector, Doc1) of
  true ->

src/mango/src/mango_native_proc.erl

@@ -118,14 +118,9 @@ get_index_entries({IdxProps}, Doc) ->
  false ->
  [];
  true ->
- Values = get_index_values(Fields, Doc),
- case lists:member(not_found, Values) of
- true -> [];
- false -> case Values of
- [{jq, Values1}] -> [[[V], null] || V <- Values1];
- _Else -> [[Values, null]]
- end
- end
+ Keys = flatten_keys(get_index_values(Fields, Doc)),
+ io:format("----[get_index_entries] ~p :: ~p~n", [Fields, Keys]),
+ [[Values, null] || Values <- Keys]
  end.
 
 get_index_values(Fields, Doc) ->
@@ -142,6 +137,17 @@ get_index_field_value({Field, FieldDef}, Doc) ->
  Value1 -> Value1
  end.
 
+flatten_keys([not_found | _]) ->
+ [];
+flatten_keys([{jq, Values} | Rest]) ->
+ Keys = flatten_keys(Rest),
+ [[V | K] || V <- Values, K <- Keys];
+flatten_keys([First | Rest]) ->
+ Keys = flatten_keys(Rest),
+ [[First | K] || K <- Keys];
+flatten_keys([]) ->
+ [[]].
+
 get_text_entries({IdxProps}, Doc) ->
  Selector = get_index_partial_filter_selector(IdxProps),
  case should_index(Selector, Doc) of

src/mango/test/22-index-function-test.py

@@ -38,12 +38,35 @@ def setUpClass(klass):
 
  create_index(
  klass.db,
- "_design/jq-split",
- "jq-split-json-index",
- {"bar_words": {"$jq": '.bar | split(" ") | .[]'}},
+ "_design/jq-split-1",
+ "jq-json-index",
+ {"f1_words": {"$jq": '.f1 | split(" ") | .[]'}},
  )
- klass.db.save_docs([{"_id": "example-doc", "bar": "a b c"}])
 
- def test_index_by_length(self):
- resp = self.db.find({"bar_words": "b"})
- self.assertEqual([doc["_id"] for doc in resp], ["example-doc"])
+ create_index(
+ klass.db,
+ "_design/jq-split-2",
+ "jq-json-index",
+ {
+ "f2_words": {"$jq": '.f2 | split(" ") | .[]'},
+ "f3_words": {"$jq": '.f3 | split(" ") | .[]'},
+ },
+ )
+
+ klass.db.save_docs(
+ [
+ {"_id": "doc-1", "f1": "a b", "f2": "j k", "f3": "y z"},
+ {"_id": "doc-2", "f1": "b c", "f2": "k l", "f3": "x y"},
+ ]
+ )
+
+ def test_search_on_one_field(self):
+ resp = self.db.find({"f1_words": "a"})
+ self.assertEqual([doc["_id"] for doc in resp], ["doc-1"])
+
+ resp = self.db.find({"f1_words": "b"})
+ self.assertEqual([doc["_id"] for doc in resp], ["doc-1", "doc-2"])
+
+ def test_search_on_two_fields(self):
+ resp = self.db.find({"f2_words": "k", "f3_words": "x"})
+ self.assertEqual([doc["_id"] for doc in resp], ["doc-2"])