eejbyfeldt opened a new pull request, #13134: URL: https://github.com/apache/datafusion/pull/13134
## Which issue does this PR close? <!-- We generally require a GitHub issue to be filed for all bug fixes and enhancements and this helps us generate change logs for our releases. You can link an issue to this PR using the GitHub syntax. For example `Closes #123` indicates that this PR will close issue #123. --> Closes #. ## Rationale for this change In https://github.com/apache/datafusion/pull/12945 the emulation of an mark join has a bug when there is duplicate values in the subquery. This would be fixable by adding a distinct before the join. This can also be resolved by using a LeftMark join. The LeftMark join exists in several other query engines. Note: This patch does not implement the full null semantics for the mark join described in http://btw2017.informatik.uni-stuttgart.de/slidesandpapers/F1-10-37/paper_web.pdf which which will be needed if we and `ANY` subqueries. The version is this patch the mark column will only be true for had a match and false when no match was found, never `null`. <!-- Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed. Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes. --> ## What changes are included in this PR? This patch instead implements a LeftMark join with the desired semantics and uses that. The LeftMark join will return a row for each in the left input with an additional column "mark" that is true if there was a match in the right input and false otherwise. This join is then used in decorrelate predicate subqueries to simplify the implementation and fix a correctness issue. <!-- There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR. --> ## Are these changes tested? Yes, new unit and fuzz tests. <!-- We typically require tests for all PRs in order to: 1. Prevent the code from being accidentally broken by subsequent changes 2. Serve as another way to document the expected behavior of the code If tests are not included in your PR, please explain why (for example, are they covered by existing tests)? --> ## Are there any user-facing changes? Fix of correctness issue with decorrelated subqueries. <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. --> <!-- If there are any breaking changes to public APIs, please add the `api change` label. --> -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
