---
title: "{ w: 1 } Asynchronous Writes and Conflict Resolution in MongoDB"
url: https://daily.dev/posts/oyq2wqhwp
source_url: https://dev.to/franckpachot/w1-asynchronous-write-and-conflict-resolution-in-mongodb-non-default-5677
type: share
source: "MongoDB_Official"
author: "Alex Bevilacqua"
published: 2026-02-10T15:03:39.757Z
updated: 2026-02-10T15:04:20.175Z
tags: ["mongodb", "distributed-systems"]
upvotes: 0
comments: 0
language: en
---

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# { w: 1 } Asynchronous Writes and Conflict Resolution in MongoDB

**[MongoDB\_Official](https://daily.dev/sources/mongodb_official)** · [@alexbevi](https://daily.dev/alexbevi) · 0 upvotes · 0 comments

## Summary

MongoDB uses Raft-inspired consensus for both leader election and data replication, guaranteeing durability and strong consistency by default with `w:majority` write concern. However, you can trade consistency for performance using `w:1`, which enables asynchronous replication but risks split-brain scenarios during network partitions. When a partition heals, MongoDB deterministically chooses the majority branch and rolls back operations from the losing side, preserving them as BSON files for manual conflict resolution. This rollback mechanism (Recover To a Timestamp) distinguishes MongoDB from vanilla Raft, allowing it to support lower latency, multi-region deployments, and migration workloads while maintaining auditability.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://dev.to/franckpachot/w1-asynchronous-write-and-conflict-resolution-in-mongodb-non-default-5677>

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---

Tags: [#mongodb](https://daily.dev/tags/mongodb), [#distributed-systems](https://daily.dev/tags/distributed-systems)

[View this post on daily.dev](https://daily.dev/posts/oyq2wqhwp)