Create individual indexes for related resources.

We were creating a compound index for all related resources of a
resource, but actually what we wanted were individual indexes for each
one: fix this state of affairs.

Author: pmcnr-hx

lib/mongoHandler.js

@@ -133,15 +133,11 @@ MongoStore._unknownError = function(err) {
 MongoStore.prototype._createIndexesForRelationships = function(collection, relationshipAttributeNames) {
   if (!Array.isArray(relationshipAttributeNames) || !relationshipAttributeNames.length) return;
 
-  var index = relationshipAttributeNames.reduce(function(partialIndex, name) {
-    if (name) {
-      partialIndex[name + ".id"] = 1;
-    }
-    return partialIndex;
-  }, {});
-  if (Object.keys(index).length) {
-    collection.createIndex(index);
-  }
+  relationshipAttributeNames.forEach(function(name) {
+    var keys = { };
+    keys[name + ".id"] = 1;
+    collection.createIndex(keys);
+  });
 };
 
 MongoStore.prototype._applySort = function(request, cursor) {