MongoEntity moe = Mongos.entity(enref);
String fieldName = moe.getFieldDbName(field);
String collName = moe.getCollectionName(q);
if (db.collectionExists(collName)) {
DBCollection coll = db.getCollection(collName);
DBObject dbq = moe.formatObject(q);
String reduce = "function(obj,prev){prev.csum+=obj." + fieldName + ";}";
GroupCommand gcmd = new GroupCommand( coll,
Mongos.dbo(),