S3 List Object Versions: Enabling Correct Ordering of Delete Markers and Object Versions

[uwe-h]

Describe the feature

Delete Markers and Object Versions should receive an additional "sort order" field in ListObjectVersions to preserve their chronological order from the API.

The correct ordering is currently an empirical observation (though hinted at in the API documentation). LastModified has a resolution of one second, which in certain high-frequency scenarios is insufficient to maintain the correct chronological sequence and strong consistency.

Use Case

Systems built on S3 that utilize Delete Markers and Object Versions in performance-critical applications may encounter this ordering issue, making it beneficial to avoid relying on workarounds.

Proposed Solution

A SortOrder member is set while deserializing ListObjectVersionsOutput with the number of the current deserialized ObjectVersion or DeleteMarker, which should be a backwards-compatible change. Here, you can find my current implementation, which uses Traits to adapt the RestXML Deserialization (not yet tested): cb24659.

Before I create a pull request, I want to bring this suggestion to be discussed and evaluated on a design basis.

Other Information

Relates to:
aws/aws-sdk-java-v2#1620
aws/aws-sdk-cpp#1649

The acknowledgement that I may implement the feature requests is currently restricted to the Go SDK

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS Go SDK V2 Module Versions Used

v1.37.2

Go version used

go1.23.6

[lucix-aws]

This is not a patch we'd accept, we can't just decide to add random fields/behaviors to service APIs like this in a random SDK. I also don't see how this would actually solve the problem, ListObjectVersions is paginated, so client-side sorting doesn't really make any sense since it only applies to one page at a time.

The only way to correctly introduce this behavior would be for the S3 service to add support for it.

[uwe-h]

Some additional information: the response from and real S3 API Call and the correct order is preserved by directly accessing the API through the split in the sdk this information gets lost:

<?xml version= \"1.0\" encoding= \"UTF-8\"?>

<ListVersionsResult xmlns= \"http://s3.amazonaws.com/doc/2006-03-01/\">
	<Name>XXXX-yknhbd4wnpp9</Name>
	<Prefix>test-ordering/7a3147f5-e5cf-4434-892e-2bea9b7c8ab4</Prefix>
	<KeyMarker></KeyMarker>
	<VersionIdMarker></VersionIdMarker>
	<MaxKeys>1000</MaxKeys>
	<EncodingType>url</EncodingType>
	<IsTruncated>false</IsTruncated>
	<DeleteMarker>
		<Key>test-ordering/7a3147f5-e5cf-4434-892e-2bea9b7c8ab4</Key>
		<VersionId>YdLK9YkamA77xxE4UoaPlWecwUKWJCYg</VersionId>
		<IsLatest>true</IsLatest>
		<LastModified>2025-08-10T10:11:53.000Z</LastModified>
	</DeleteMarker>
	<Version>
		<Key>test-ordering/7a3147f5-e5cf-4434-892e-2bea9b7c8ab4</Key>
		<VersionId>YPXCegCLAvwbg_5HUssLd8p3ReQ6qKgT</VersionId>
		<IsLatest>false</IsLatest>
		<LastModified>2025-08-10T10:11:53.000Z</LastModified>
		<ETag>&quot;27ddd45b69e721be1dec90860cb39c5e&quot;</ETag>
		<ChecksumAlgorithm>CRC32</ChecksumAlgorithm>
		<ChecksumType>FULL_OBJECT</ChecksumType>
		<Size>9</Size>
		<StorageClass>STANDARD</StorageClass>
	</Version>
	<DeleteMarker>
		<Key>test-ordering/7a3147f5-e5cf-4434-892e-2bea9b7c8ab4</Key>
		<VersionId>6.GLV4MTevm5GrWqZwZFA25J7cjkMAUo</VersionId>
		<IsLatest>false</IsLatest>
		<LastModified>2025-08-10T10:11:53.000Z</LastModified>
	</DeleteMarker>
	<Version>
		<Key>test-ordering/7a3147f5-e5cf-4434-892e-2bea9b7c8ab4</Key>
		<VersionId>LJrEjB4nCyrOy1zSx2kTDtCFFqOm_lKv</VersionId>
		<IsLatest>false</IsLatest>
		<LastModified>2025-08-10T10:11:53.000Z</LastModified>
		<ETag>&quot;6deb7d5ca68840f07d8e56764c8dc673&quot;</ETag>
		<ChecksumAlgorithm>CRC32</ChecksumAlgorithm>
		<ChecksumType>FULL_OBJECT</ChecksumType>
		<Size>9</Size>
		<StorageClass>STANDARD</StorageClass>
	</Version>

</ListVersionsResult>
``

[lucix-aws]

I'm not following, are you saying the SDK is somehow corrupting the order of the serialized list?

[uwe-h]

The order within each separated Version and DeleteMarker List is correct. To bring both lists in order, you need to have a sort criterion that allows you to do so. If the PutObject and DeleteObject there below the 1-second time resolution, it is impossible to sort by last modified (see example response). However, S3 returns it in the expected order. In other words, the split in separate lists in the SDK or the time resolution provided by S3 of the Last Modified field.

There might be better solutions than using a new field sort order. My idea tries to keep backwards compatibility.

I could not find a statement about the ordering of both constructs. I somehow concluded it from example responses and through a repeatable test case directly against the API. The example response is from such a test. In the Java SDK Issue Link above, with more information, and also a hint that it might affect all SDKs.