正如Mongodb手册所述,"db.collection.group()方法不适用于分片群集.在分片环境中使用聚合框架或map-reduce." 但是今天,我惊讶地发现它适用于Java驱动程序.
在我的测试中,分片集合称为"spams",其中包含4,001,633个文档.它以7个分片分片.
集合中的每个文档都有这样的格式.
shard1:PRIMARY> db.spams.findOne()
{
"IP" : "113.162.134.245",
"_id" : ObjectId("4ebe8c84466e8b1a56000028"),
"attach" : [ ],
"bot" : "Lethic",
"charset" : "iso-8859-1",
"city" : "",
"classA" : "113",
"classB" : "113.162",
"classC" : "113.162.134",
"content_type" : [ ],
"country" : "Vietnam",
"cte" : "7bit",
"date" : ISODate("2011-11-11T00:07:12Z"),
"day" : "2011-11-11",
"from_domain_a" : "domain157939.com",
"geo" : "VN",
"host" : "",
"lang" : "unknown",
"lat" : 16,
"long" : 106,
"sequenceID" : "user648",
"size" : 1060,
"smtp-mail-from_a" : "barriefrancisco@domain157939.com",
"smtp-rcpt-to_a" : …