[adapters] Delta: process delete actions before adds. #5499
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Semantically, delete actions in a delta lake log entry are applied before insert actions; however the delta spec doesn't guarantee that actions occur in any particular order. This commit makes sure that delete actions are processed before inserts. Signed-off-by: Leonid Ryzhyk <[email protected]>
Contributor
There was a problem hiding this comment.
Pull request overview
This PR ensures correct ordering of Delta Lake transaction log actions by processing delete operations before insert operations. While the Delta Lake specification defines that deletes semantically precede inserts, it doesn't guarantee action ordering in the log files.
Changes:
- Separated action processing into two passes: first handling
Removeactions, thenAddactions - Added explanatory comments documenting the semantic ordering requirement from the Delta Lake specification
Comment on lines
+1693
to
+1694
| for action in actions { | ||
| if matches!(action, Action::Add(_)) { |
There was a problem hiding this comment.
The actions collection is iterated twice (once for Remove, once for Add). Consider using partition or a single-pass approach with separate collections to avoid the second full iteration over all actions.
mihaibudiu
approved these changes
Jan 23, 2026
swanandx
approved these changes
Jan 23, 2026
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Semantically, delete actions in a delta lake log entry are applied before insert actions; however the delta spec doesn't guarantee that actions occur in any particular order.
This commit makes sure that delete actions are processed before inserts.