Realm Primary Key Insert Performance @ 1 million + 1 records

models.swift

import Foundation
import RealmSwift


class StringObject: Object{
    dynamic var id: String = ""

    override static func primaryKey() -> String{
        return "id"
    }
}

class IntObject: Object{
    dynamic var id: Int = 0

    override static func primaryKey() -> String{
        return "id"
    }

}

testInt.swift

func testIntPerformanceExample() {
    let realm = db.realm

    let ids = (0..<max).map{ i -> IntObject in
        let obj = IntObject()
        obj.id = i
        return obj
    }


    try! realm.write {
        ids.forEach{ obj in
            realm.add(obj)
        }
    }


    let obj = IntObject()
    obj.id = max + 1

    self.measureBlock {
        try! realm.write {
            realm.add(obj)
        }
    }
}

testUUID.swift

func testUUIDPerformanceInsertPerformance() {
    let realm = db.realm

    let ids = (0..<max).map{ _ -> StringObject in
        let obj = StringObject()
        obj.id = NSUUID().UUIDString
        return obj
    }

    try! realm.write {
        ids.forEach{ obj in
            realm.add(obj)
        }
    }
    
    let obj = StringObject()
    obj.id = NSUUID().UUIDString

    self.measureBlock {
        try! realm.write {
            realm.add(obj)
        }
    }
}