Does multiple updates on single document in a transaction incur write cost for each update separately in Firestore

Question

For example will update(sfDocRef, "population", newPopulation) and update(sfDocRef, "count", newCount) be counted as separate document write. Or should i use set() method

db.runTransaction { transaction ->
    val snapshot = transaction.get(sfDocRef)

    val newPopulation = snapshot.getDouble("population")!! + 1
    val newCount = snapshot.getLong("count")!! + 1
    it.apply {
         update(sfDocRef, "population", newPopulation)
         update(sfDocRef, "count", newCount)
    }  
}

Answer 1

It is considered as a seperate write operation. It is better to combine those. I think this will help you. Link