The default behavior in DataOps for comparing changes between branches or commits is to use the "git diff from...to" format, which compares the differences based on the merge base. This format considers the shared history and common ancestor when presenting the differences. However, it may not handle cherry-picked or rebased commits correctly in certain cases.
Cherry-picking involves applying specific commits from one branch to another, selectively incorporating individual changes while skipping others. The issue with cherry-picks and the "git diff from...to" format arises because cherry-picked commits have different commit hashes compared to their original commits.
When using the "git diff from...to" format, Git compares the merge base with the "to" commit, including any cherry-picked commits along the way. Due to the different commit hashes, Git considers cherry-picked commits as entirely new changes, even if they introduce identical content. Consequently, the diff output can be confusing, displaying cherry-picked changes as new additions or modifications instead of recognizing them as the same changes already present in the merge base.
To address this issue and accurately handle cherry-picked commits, it is recommended to use the "git diff from to" format, utilising the double-dot (..) notation. This format compares the differences between the specified branches or commits while excluding the specified commits. However, it is important to note that the DataOps platform's user interface does not currently support this format, requiring users to perform the comparison locally using Git commands.
By employing the "git diff from to" format, Git compares the actual commit content between the "from" and "to" commits, providing a more precise representation of the differences, particularly when cherry-picks are involved. While DataOps primarily employs the "git diff from...to" format, it is crucial to recognize that Git offers alternative ways to compare changes, including the "git diff from to" format. If specific requirements or a different comparison format are desired, resorting to Git commands on the local machine is recommended alongside the DataOps web interface.
Workaround for Comparisons in the DataOps User Interface:
As a supplementary approach to the aforementioned limitation, a workaround can be applied to facilitate comparisons in the DataOps user interface. Suppose you aim to compare branches "foo" and "bar" for merging "foo" into "bar." The following procedure can be employed:
- Create a new branch called "bar-plus-foo" based on "bar."
- Merge "foo" into "bar-plus-foo."
- Compare "bar-plus-foo" with "bar."
This method allows for a comparison that takes into account the cherry-picked commits, providing a more accurate depiction of the differences between the branches. Additionally, it is advisable to perform a "git pull" of the branch from which a new feature branch will be created before checking out and creating the new feature branch. This ensures starting from the latest commit in the origin, preventing it from being treated as a cherry-pick later on.
Considering Individual Commits and Context for Meaningful Comparisons:
Directly comparing branches may prove inadequate in certain scenarios as it overlooks the individual commits and their context. To illustrate this point, consider a scenario where two branches, A and B, are to be merged. Branch A consists of five commits, while branch B has three commits. A direct comparison of the branches would merely indicate differences without considering the specific changes made in each commit.
However, the content of those commits can be crucial. For instance, one of the commits in branch A might address a critical bug, while another introduces a new feature. In branch B, one commit may refactor code, and another may involve documentation changes.
By utilising a merge or pull request, it becomes possible to review and discuss each commit individually, comprehend the purpose of the changes, and ensure their proper integration into the target branch. This approach enables a more comprehensive and meaningful review of the changes before merging.
Rebasing can indeed contribute to the problem described. Rebasing alters the commit history by placing the rebased branch on top of the target branch, potentially causing conflicts due to overlapping changes or previous work based on the original branch.
While local operations offer more flexibility, UI-driven merge requests play a vital role in workflows, particularly when working with protected branches. Collaborating with team members and enforcing specific rules and policies often necessitates the use of the UI-driven approach.
In the case of merge conflicts related to the suggested "bar-plus-foo" approach, it is possible that the conflicts were unrelated to the suggested method. Merge conflicts can arise from various factors, such as conflicting changes between branches or incorrect conflict resolution during the merge process.
As an additional workaround, external tools can be employed. For example, when using DataOps DDE or IDEs like VSCode or JetBrains, extensions such as Gitlens or Git Toolbox can be utilized. These extensions provide comparisons between any two recorded commits, simulating the experience and offering increased flexibility.
In summary, understanding the different Git diff formats and their implications, as well as considering individual commits and their context, is essential for effective comparison and review of changes in DataOps. While the platform primarily employs the "git diff from...to" format, using the "git diff from to" format locally is recommended for accurate handling of cherry-picked commits. Additionally, alternative workflows and external tools can further enhance the comparison process and provide additional flexibility when needed.