This operation completes a multipart upload by assembling previously uploaded parts.
You first initiate the multipart upload and then upload all parts using the Upload Parts
operation (see Upload Part). After successfully uploading all relevant parts of an upload, you
call this operation to complete the upload. Upon receiving this request, Amazon S3
concatenates all the parts in ascending order by part number to create a new object. In the
Complete Multipart Upload request, you must provide the parts list. For each part in the list,
you must provide the part number and the ETag header value, returned after that part was
uploaded.
Processing of a Complete Multipart Upload request could take several minutes to complete.
After Amazon S3 begins processing the request, it sends an HTTP response header that specifies
a 200 OK response. While processing is in progress, Amazon S3 periodically sends whitespace
characters to keep the connection from timing out. Because a request could fail after the
initial 200 OK response has been sent, it is important that you check the response body to
determine whether the request succeeded.
Note that if Complete Multipart Upload fails, applications should be prepared to retry the
failed requests.