Completing a Multipart Upload

Functions

After all parts are uploaded, you can call this API to assemble specified parts into an object. Before performing this operation, you cannot download the uploaded data. When merging parts, you need to copy the additional message header information recorded during the initialization of the multipart upload task to the object metadata. The processing process is the same as that of the common upload object with these message headers. In the case of merging parts concurrently, the Last Write Win policy must be followed but the time for initiating Last Write is specified as the time when a part multipart upload is initiated.

If a multipart upload has not been aborted, the uploaded parts occupy your storage quota. After all parts in the multipart upload are merged to an object, only the object occupies your storage quota. If a part uploaded in a multipart upload is not used in any merging parts multipart uploads, the part will be deleted to release storage quota.

You can send a request for downloading all or some data of the generated multipart by specifying a range.

You can send a request for deleting all parts uploaded in a multipart upload. Deleted data cannot be restored.

The merged parts do not use the MD5 value of entire object as the ETag. Their ETag is calculated as follows: MD5(M1M2...MN)-N, where Mn is the MD5 value of part n (N is the total number of parts). As described in the Sample Request, there are three parts and each part has an MD5 value. The MD5 values of the three parts are recalculated to obtain a new MD5 value. Then -N is added to the right of the MD5 value to get the ETag of the combined parts. In this example, -N is -3.

If the response to an object assembling request timed out and error 500 or 503 was returned, you can first obtain the object metadata of the multipart upload task. Then, check whether the value of header x-obs-uploadId in the response is the same as the ID of the current multipart upload task. If they are, it means the object parts have been successfully assembled on the server and you do not need to try again. For details, see Consistency of Concurrent Operations.

WORM

If a bucket has WORM enabled, the WORM protection will be automatically applied to the object generated after a multipart upload is complete. If you specify WORM headers and a retention expiration date when you initiate a multipart upload, the protection for the assembled object ends on the specified date. If you do not specify WORM headers during the initiation, but have configured the default bucket-level retention policy, this default policy is automatically applied and the protection starts when the multipart upload is complete. After a multipart upload is complete, you can still configure object-level WORM retention policies for the assembled object.

Versioning

If a bucket has versioning enabled, a unique version ID is generated for an object created from a multipart upload in this bucket and the version ID is returned in response header x-obs-version-id. If versioning is suspended for a bucket, the object version obtained after the merge is null. For details about the versioning statuses of a bucket, see Configuring Versioning for a Bucket.

Important

If 10 parts are uploaded but only nine parts are selected for merge, the parts that are not merged will be automatically deleted by the system. The parts that are not merged cannot be restored after being deleted. Before combining the parts, adopt the interface used to list the parts that have been uploaded to check all parts to ensure that no part is missed.

Request Syntax

POST /ObjectName?uploadId=uploadID HTTP/1.1
Host: bucketname.obs.region.example.com
Date: date
Content-Length: length
Authorization: authorization
<CompleteMultipartUpload>
    <Part>
        <PartNumber>partNum</PartNumber>
        <ETag>etag</ETag>
    </Part>
    <Part>
        <PartNumber>partNum</PartNumber>
        <ETag>etag</ETag>
    </Part>
    <Part>
        <PartNumber>partNum</PartNumber>
        <ETag>etag</ETag>
    </Part>
</CompleteMultipartUpload>

Request Parameters

This request uses parameters to specify the ID of a multipart upload whose parts will be assembled. Table 1 describes the parameters.

Table 1 Request parameters

Parameter

Type

Mandatory (Yes/No)

Description

uploadId

String

Yes

Explanation:

Multipart upload ID.

Value range:

The value must contain 32 characters.

Default value:

None

Request Headers

This request uses common headers. For details, see Table 3.

Request Elements

This request uses elements to specify the list of parts to be assembled. Table 2 describes the elements.

Table 2 Request elements

Element

Type

Mandatory (Yes/No)

Description

CompleteMultipartUpload

XML

Yes

Explanation:

List of parts to be assembled

Restrictions:

None

Value range:

None

Default value:

None

PartNumber

Integer

Yes

Explanation:

Part number

Restrictions:

None

Value range:

[1,10000]

Default value:

None

ETag

String

Yes

Explanation:

ETag value returned upon successful upload of a part. It is the unique identifier of the part content. This parameter is used to verify data consistency when parts are merged.

Restrictions:

None

Value range:

The value must contain 32 characters.

Default value:

None

Response Syntax

HTTP/1.1 status_code
Date: date
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<CompleteMultipartUploadResult xmlns="http://obs.region.example.com/doc/2015-06-30/">
    <Location>http://example-Bucket.obs.region.example.com/example-Object</Location>
    <Bucket>bucketname</Bucket>
    <Key>ObjectName</Key>
    <ETag>ETag</ETag>
</CompleteMultipartUploadResult>

Response Headers

The response to the request uses common headers. For details, see Table 1.

In addition to the common response headers, the message headers listed in Table 3 may be used.

Table 3 Additional response headers

Header

Type

Description

x-obs-version-id

String

Explanation:

Version of the object after parts are assembled.

Restrictions:

None

Value range:

The value must contain 32 characters.

Default value:

None

x-obs-server-side-encryption

String

Explanation:

The encryption method used by the server.

Example: x-obs-server-side-encryption:kms

Restrictions:

This header is included in a response if SSE-KMS is used.

Value range:

  • kms

  • AES256

Default value:

None

x-obs-server-side-encryption-kms-key-id

String

Explanation:

ID of a specified key used for SSE-KMS encryption.

Restrictions:

This header can only be used when you specify kms for the x-obs-server-side-encryption header.

Default value:

If you specify kms for encryption but do not specify a key ID, the default master key will be used. If there is not a default master key, OBS will create one and use it.

x-obs-server-side-encryption-customer-algorithm

String

Explanation:

The algorithm used for encryption.

Example: x-obs-server-side-encryption-customer-algorithm:AES256

Restrictions:

This header is included in a response if SSE-C is used for server-side encryption.

Value range:

AES256

Default value:

None

Response Elements

This response uses elements to return the result of assembling parts. Table 4 describes the elements.

Table 4 Response elements

Element

Type

Description

Location

String

Explanation:

Path of the object after parts are assembled.

Restrictions:

Format: /bucketName/objectName

Value range:

None

Default value:

None

Bucket

String

Explanation:

Bucket where parts are assembled

Restrictions:

  • A bucket name must be unique across all accounts and regions.

  • A bucket name:

    • Must be 3 to 63 characters long and start with a digit or letter. Lowercase letters, digits, hyphens (-), and periods (.) are allowed.

    • Cannot be formatted as an IP address.

    • Cannot start or end with a hyphen (-) or period (.).

    • Cannot contain two consecutive periods (..), for example, my..bucket.

    • Cannot contain a period (.) and a hyphen (-) adjacent to each other, for example, my-.bucket or my.-bucket.

  • If you repeatedly create buckets of the same name in the same region, no error will be reported and the bucket attributes comply with those set in the first creation request.

Value range:

None

Default value:

None

Key

String

Explanation:

Object name obtained after part assembling.

An object is uniquely identified by an object name in a bucket. An object name is a complete path that does not contain the bucket name.

Restrictions:

None

Value range:

The value must contain 1 to 1,024 characters.

Default value:

None

ETag

String

Explanation:

The ETag that uniquely identifies the object after its parts were assembled, calculated based on the ETag of each part.

Restrictions:

If an object is encrypted using server-side encryption, the ETag is not the MD5 value of the object.

Value range:

The value must contain 32 characters.

Default value:

None

Error Responses

  1. If no message body exists, OBS returns 400 Bad Request.

  2. If the message body format is incorrect, OBS returns 400 Bad Request.

  3. If the part information in the message body is not sorted by part sequence number, OBS returns 400 Bad Request and the error code is InvalidPartOrder.

  4. If the AK or signature is invalid, OBS returns 403 Forbidden and the error code is AccessDenied.

  5. If the requested bucket is not found, OBS returns 404 Not Found and the error code is NoSuchBucket.

  6. If the requested multipart upload does not exist, OBS returns 404 Not Found and error code NoSuchUpload.

  7. If the user is not the initiator of the task, OBS returns 403 Forbidden and the error code is AccessDenied.

  8. If the request part list contains a part that does not exist, OBS returns 400 Bad Request and the error code is InvalidPart.

  9. If the part's ETag contained in the request list is incorrect, OBS returns 400 Bad Request with an error code of InvalidPart.

  10. If the size of a part other than the last part is smaller than 100 KB, OBS returns 400 Bad Request.

  11. If the size of the object is greater than 48.8 TB after parts being merged, OBS returns status code 400 Bad Request.

Other errors are included in Table 2.

Sample Request

POST /object02?uploadId=00000163D46218698DF407362295674C HTTP/1.1
User-Agent: curl/7.29.0
Host: examplebucket.obs.region.example.com
Accept: */*
Date: WED, 01 Jul 2015 05:23:46 GMT
Authorization: OBS H4IPJX0TQTHTHEBQQCEC:dOfK9iILcKxo58tRp3fWeDoYzKA=
Content-Length: 422

<?xml version="1.0" encoding="utf-8"?>
<CompleteMultipartUpload>
  <Part>
    <PartNumber>1</PartNumber>
    <ETag>a54357aff0632cce46d942af68356b38</ETag>
  </Part>
  <Part>
    <PartNumber>2</PartNumber>
    <ETag>0c78aef83f66abc1fa1e8477f296d394</ETag>
  </Part>
  <Part>
    <PartNumber>3</PartNumber>
    <ETag>acbd18db4cc2f85cedef654fccc4a4d8</ETag>
  </Part>
</CompleteMultipartUpload>

Sample Response

HTTP/1.1 200 OK
Server: OBS
x-obs-request-id: 8DF400000163D4625BE3075019BD02B8
x-obs-id-2: 32AAAQAAEAABAAAQAAEAABAAAQAAEAABCSN8D1AfQcIvyGBZ9+Ee+jU6zv1iYdO4
Content-Type: application/xml
Date: WED, 01 Jul 2015 05:23:46 GMT
Content-Length: 326

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<CompleteMultipartUploadResult xmlns="http://obs.example.com/doc/2015-06-30/">
  <Location>/examplebucket/object02</Location>
  <Bucket>examplebucket</Bucket>
  <Key>object02</Key>
  <ETag>"03f814825e5a691489b947a2e120b2d3-3"</ETag>
</CompleteMultipartUploadResult>
last updated: 2024-12-11 10:27 UTC - commit: 1084b97f9d241d7af788bdfaa536dba9679533f7