我有一个集合,每个文档的格式如下
{access_key:'xxxxxxxxx', keyword: "banana", count:12, request_hour:"Thu Sep 30 2010 12:00:00 GMT+0000 (UTC)"}
{access_key:'yyyyyyyyy', keyword: "apple", count:25, request_hour:"Thu Sep 30 2010 12:00:00 GMT+0000 (UTC)", }
.....
为了实现这个目标:
SELECT keyword, sum(count) FROM keywords_counter WHERE access_key = 'xxxxxxxxx' GROUP BY keyword
我正在做以下工作:db.keywords_counter.group({key : {keyword:true},
cond : {access_key: "xxxxx"},
reduce : function(obj, prev){prev.total += obj.count},
initial : {total:0}})
我该如何使用map/reduce实现相同的功能?[我是一个map/reduce的初学者,正在努力理解这个概念。]