Expose the loaded_version and saved_version for AbstractVersionedDataSet

[noklam]

Signed-off-by: Nok Chan [email protected]

Description

Related #1580

How current load version is determined when version=None?

Currently, this load_version information is buried deep down in the framework, and it is determined only when a dataset is loaded at runtime.
The details of how "latest" version is in a method called resolve_load_version, which further calls _fetch_latest_load_version

kedro/kedro/io/core.py

Lines 558 to 564 in b2e59fa

	def _get_load_path(self) -> PurePosixPath:
	if not self._version:
	# When versioning is disabled, load from original filepath
	return self._filepath
	load_version = self.resolve_load_version()
	return self._get_versioned_path(load_version) # type: ignore

How version is determined?

  def resolve_load_version(self) -> Optional[str]:
      """Compute the version the dataset should be loaded with."""
      if not self._version:  # Not version at all - not sure when will this path executed?
          return None 
      if self._version.load:  # when load-version is specified in CLI or config
          return self._version.load
      return self._fetch_latest_load_version().  # When version=None

Development notes

Checklist

• Read the contributing guidelines
• Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• Updated the documentation to reflect the code changes
• Added a description of this change in the RELEASE.md file
• Added tests to cover my changes

Alternatives

1st attempt - Add new attributes in AbstractVersionedDataSet

It may not be a bad idea to add new attributes at all - we can update the load_version save_version or the version_cache, but that way we also lost the initial input which makes things complicated.

8fe0b1a

More Context

• https://github.com/quantumblacklabs/private-kedro/pull/404

Currently every call to AbstractVersionedDataSet.load() resolves the load version once again. This may result in inconsistent versioned being passed to different nodes (if new version is created mid-run).

[noklam]

Closed in favor of #1654 as the pre-requisite and we should come back to think about how to expose these information.