Preferred method to mass update in Realm?

Question

I have 10,000 Person Objects in my Realm database, all I have are the IDs of each person. I've been profiling the different solutions I have come up with to update all the names on each Person object.

In my test application I retrieve all the IDs using the following.

The code below is only run to fetch IDs for the tests, in the real application I would already have the IDs

var ids = [String]()
for person in realm.objects(Person) {
    ids.append(person.id)
}

First approach to update all names for 10,000 Person objects

realm.write {
    let people = realm.objects(Person).filter("id IN %@", ids)
    for person in people {
        person.name = "lionpants"
    }
}

Second approach to update all names for 10,000 Person objects

realm.write {
    for id in ids {
        let person = realm.objectForPrimaryKey(Person.self, key: id)
        person?.name = "lionpants"
    }
}

Surprisingly both approaches averaged about 1200ms runtime (including fetching the IDs) using the Xcode Time Profiler (I thought the first approach with the predicate would be faster).

Personally, I prefer the second approach due to the lack of predicates. But, is there a preferred/different approach when mass updating with Realm? Maybe I'm missing some built in functions?

Answer 1

realm.write {
    let people = realm.objects(Person).filter("id IN %@", ids)
    people.setValue("lionpants", forKey: "name")
}

Should be slight faster, and in general using KVC on results like that will be more performant, as Realm can take some shortcuts under the hood.