mongo聚合和mapreduce例子

聚合语句-比较集合内两字段大小
db.test.aggregate([
{$match:{"offlineTime":{$gt:ISODate("2016-09-13T01:54:55Z"), "$lt":ISODate("2016-09-13T10:05:55Z")},"logType":"off"}},
{$project:{updateTime:1,offlineTime:1,offTimeInc:{$add:['$offlineTime',1800000]},mac:1}},
{$project:{updateTime:1,offlineTime:1,offTimeInc:1,mac:1,eq:{$cond:[{$gt:['$updateTime','$offTimeInc']}, 1, 0]}}},
{$match:{eq:1}}
])

聚合条数语句
db.tableName.aggregate([
{$match:{"offlineTime":{$gt:ISODate("2016-09-13T01:54:55Z"), "$lt":ISODate("2016-09-13T10:05:55Z")},"logType":"off"}},
{$project:{updateTime:,offlineTime:,offTimeInc:{$add:['$offlineTime',]},mac:}},
{$project:{updateTime:,offlineTime:,offTimeInc:,mac:,eq:{$cond:[{$gt:['$updateTime','$offTimeInc']}, , ]}}},
{$match:{eq:}},
{$group:{_id:null, total:{$sum:}}}
])

简单聚合语句

db.test.aggregate( [
                        { $match : {  start:{$gte: , $lte: }, buildingId: , intfType:"uplink", utcCode:} },
                        { $group: { _id: {buildingId:"$buildingId", mac:"$mac"}, rxtxByteTotal: { $sum: "$rxTxBytes" } } }
                       ] );

简单的mapreduce

var map = function(){
    emit({"buildingId" : this.buildingId , "mac" : this.mac , "utcCode" : this.utcCode},  {"wifiUpDown" : this.wifiUpDown , "activeTime" : this.activeTime });
}

var reduce = function(key, values){
    var wifi = ;
    var activeTime = ;
    values.forEach(function(val){
        wifi += val.wifiUpDown;
        activeTime += val.activeTime;
    })
    return {"wifi": wifi, "activeTime": activeTime};
}
db.test.mapReduce(map,reduce,{out:"mr2"})
上述为shell中直接执行的脚本。
使用spring-data-mongodb的版本：

String inCollectionName =  "test";
String mapFunction = "function(){"
                        + "emit({buildingId : this.buildingId , "
                        + "mac : this.mac , utcCode : this.utcCode}, "
                                        + " {wifiUpDown : this.wifiUpDown , "
                                        + "activeTime : this.activeTime });}";
String reduceFunction = "function(key, values){ "
                        + "var wifi = 0;"
                        + "var activeTime = 0;"
                        + "values.forEach(function(val){ "
                        + "wifi += val.wifiUpDown;"
                        + "activeTime += val.activeTime;"
                        + " });"
                        + " return {wifi: wifi, activeTime: activeTime};"
                                + "}";
List<Test> result = new ArrayList<>();
mongo.mapReduce(inCollectionName, mapFunction, reduceFunction, Test.class).forEach(
                    data->result.add(data)    );
result.forEach(data->System.out.println(JSON.toJSONString(data)));

带project的聚合例子

db.test.aggregate( [
    { $match : {  day:} },
    { $group: { _id: {buildingId:"$buildingId", intfType:"$intfType", aggregatedTime:"$aggregatedTime", day:"$day"}
    , rxTxBytes: { $sum: "$rxTxBytes" }
    , rxBytes: {$sum: "$rxBytes"}
    , txBytes: {$sum: "$txBytes"}
    , rxPkts: {$sum: "$rxPkts"}
    , txPkts: {$sum: "$txPkts"}
     } },
    { $project:{"_id":, buildingId: "$_id.buildingId", intfType:"$_id.intfType", day:"$_id.day", rxBytes:, rxPkts:, txBytes:, txPkts:, aggregatedTime:"$_id.aggregatedTime", rxTxBytes:} }
] );