记录几个常用mongodb命令

去重

db.record.aggregate([{

    $group: {

        _id: {

            field: '$field'

        },

        count: {

            $sum: 1

        },

        dups: {

            $addToSet: '$_id'

        }

    }

},

{

    $match: {

        count: {

            $gt: 1

        }

    }

}]).forEach(function(it) {

    it.dups.shift();

    db.record.remove({

        _id: {

            $in: it.dups

        }

    });

});

forEach 修改

db.record.find({

    type: 1,

    field: {

        '$exists': false

    }

}).forEach(function(it) {

    var s = 0;

    it.list.forEach(function(item) {

        s += NumberInt(item.score);

    });

    it.field= s / 5;

    db.record.save(it);



});

建立索引

db.record.createIndex({

    field: 1

},

{unique: true})