看到 Amazon S3 宣佈 Strong Read-After-Write Consistency 了：「Amazon S3 Update – Strong Read-After-Write Consistency」。

這個問題從很久前就被討論過：

所以到這次更新之前，只有新增的 object 會保證馬上出現。現在則是 update 也會：

Effective immediately, all S3 GET, PUT, and LIST operations, as well as operations that change object tags, ACLs, or metadata, are now strongly consistent. What you write is what you will read, and the results of a LIST will be an accurate reflection of what’s in the bucket. This applies to all existing and new S3 objects, works in all regions, and is available to you at no extra charge! There’s no impact on performance, you can update an object hundreds of times per second if you’d like, and there are no global dependencies.

要注意這邊沒有提到 DELETE，所以有可能 DELETE + GET 的操作還是沒有到 strong consistency，不過句子本身意思不是很清晰，也許這幾天會有人在 forum 上面問然後有答案...

另外從公告裡面提到 Amazon EMR 團隊，看起來是 Amazon EMR 團隊一直在內部戳 Amazon S3 的團隊改善：

We’ve been working with the Amazon EMR team and developers in the open-source community to ensure that customers can take advantage of this update with their big data workloads. As a result of that you no longer need to use EMRFS Consistent View or S3Guard, further reducing the cost to run big data workloads in AWS.