Versioning
If you enable versioning for a bucket, Amazon S3 automatically generates a unique
version ID for the object being stored. Amazon S3 returns this ID in the response using
the x-amz-version-id
response header. If versioning is suspended,
Amazon S3 always uses null
as the version ID for the object stored. For
more information about returning the versioning state of a bucket, see GET Bucket (Versioning
Status).
If you enable versioning on a bucket, when Amazon S3 receives multiple write requests for the same object simultaneously, all of the objects will be stored.
To see sample requests that use versioning, see Sample Request.