MongoDB shardCollection command in Go

Question

I'm trying to shard a collection using mgo library in Go. Looks like I can't figure out to run commands using Session.Run call. Here is my code:

if err := session.DB("admin").Run(bson.D{{"shardCollection", "visits.visits-2016-05"}, {"uuid", "1"}}, &result); err != nil {
    panic(err)
} else {
    fmt.Println(result)
}

I've tried several variants of passing key parameter, but I'm always getting no shard key error

What am I doing wrong here?

Answer 1

I think the issue you're having is that you have to specify that the second field is the key of key and the value is the subdocument of {uuid: 1}. This way you're matching the exact fields listed by the mongo documentation: https://docs.mongodb.org/manual/reference/command/shardCollection/.

The code I'm using for the same process is:

if err := adminDb.Run(
            bson.D{
                {
                    "shardCollection",
                    "logs.log_"+dateString,
                },
                {
                    "key",
                    bson.M{
                        "sk": "hashed",
                    },
                },
            }, &result); err != nil {
                log.Println("Failed to shardCollection logs.log_"+dateString, err)
            }

So you might want to try

if err := session.DB("admin").Run(bson.D{{"shardCollection", "visits.visits-2016-05"}, {"key", bson.M{"uuid", "1"}}}, &result); err != nil {
    panic(err)
} else {
    fmt.Println(result)
}