COUCHDB-861 - enhance _sum to work with lists of numbers.

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@987343 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 19 insertions, 2 deletions

diff --git a/src/couchdb/couch_query_servers.erl b/src/couchdb/couch_query_servers.erl
index 92c30f82..6fc806f9 100644
--- a/src/couchdb/couch_query_servers.erl
+++ b/src/couchdb/couch_query_servers.erl
@@ -165,12 +165,29 @@ builtin_reduce(Re, [<<"_stats",_/binary>>|BuiltinReds], KVs, Acc) ->
 
 builtin_sum_rows(KVs) ->
     lists:foldl(fun
-        ([_Key, Value], Acc) when is_number(Value) ->
+        ([_Key, Value], Acc) when is_number(Value), is_number(Acc) ->
             Acc + Value;
+        ([_Key, Value], Acc) when is_list(Value), is_list(Acc) ->
+            sum_terms(Acc, Value);
+        ([_Key, Value], Acc) when is_number(Value), is_list(Acc) ->
+            sum_terms(Acc, [Value]);
+        ([_Key, Value], Acc) when is_list(Value), is_number(Acc) ->
+            sum_terms([Acc], Value);
         (_Else, _Acc) ->
-            throw({invalid_value, <<"builtin _sum function requires map values to be numbers">>})
+            throw({invalid_value, <<"builtin _sum function requires map values to be numbers or lists of numbers">>})
     end, 0, KVs).
 
+sum_terms([], []) ->
+    [];
+sum_terms([_|_]=Xs, []) ->
+    Xs;
+sum_terms([], [_|_]=Ys) ->
+    Ys;
+sum_terms([X|Xs], [Y|Ys]) when is_number(X), is_number(Y) ->
+    [X+Y | sum_terms(Xs,Ys)];
+sum_terms(_, _) ->
+    throw({invalid_value, <<"builtin _sum function requires map values to be numbers or lists of numbers">>}).
+
 builtin_stats(reduce, [[_,First]|Rest]) when is_number(First) ->
     Stats = lists:foldl(fun([_K,V], {S,C,Mi,Ma,Sq}) when is_number(V) ->
         {S+V, C+1, erlang:min(Mi,V), erlang:max(Ma,V), Sq+(V*V)};