[ryanworl]

You cannot replace DynamoDB with S3. S3 can not perform atomic and strongly consistent operations.

Edit: as other commenters have noted, you can perform a read after write on a new key.

[andrewguenther]

S3 is atomic, but you are correct that it is not strongly consistent.

[monkmartinez]

I am pretty sure S3 is atomic. That is, you can't get a transitory state. Your object either updated/PUT or it didn't AKA read after write consistency.

[moduspol]

Only if you haven't already asked for that new key. :)