{
    "search_param.departure_airport" : 1,
    "search_param.arrival_airport" : 1,
    "search_param.departure_date" : 1,
    "search_param.arrival_date" : 1    
}
过期时间：三天
259200  （秒）

> db.airticket.ensureIndex({"search_param.departure_airport" : 1,"search_param.arrival_airport" : 1,"search_param.departure_date" : 1,"search_param.arrival_date" : 1})

{
    "ok" : 0,
    "errmsg" : "namespace name generated from index name \"airline.airticket.$search_param.departure_airport_1_search_param.arrival_airport_1_search_param.departure_date_1_search_param.arrival_date_1\" is too long (127 byte max)",
    "code" : 67,
    "codeName" : "CannotCreateIndex"
}

名字过长：

db.airticket.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index","background":true})
db.airticket_parse_error.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})
db.bravofly.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index","background":true})
db.budgetair.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index","background":true})
db.omega.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})
db.gotogate.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})

db.skiddoo.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})
db.tripsta.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})
db.easyjet.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})
db.hutchgo.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index"})

db.bravofly_android.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index","background":true})
db.expedia.ensureIndex({"search_param.departure_airport" : 1,    "search_param.arrival_airport" : 1,    "search_param.departure_date" : 1,    "search_param.arrival_date" : 1    },{"name":"search_param_index","background":true})