alamb opened a new pull request, #7747: URL: https://github.com/apache/arrow-datafusion/pull/7747
## Which issue does this PR close? Related to https://github.com/apache/arrow-datafusion/pull/7699 ## Rationale for this change I am somewhat embarrassed that I did not fully understand @Dandandan 's fix in https://github.com/apache/arrow-datafusion/pull/7699/files and then spent some non trivial time tracking the same issue down in IOx and filed a ticket https://github.com/apache/arrow-datafusion/issues/7746 only to find it had already been fixed ## What changes are included in this PR? Add some comments to try and explain the change more generally BTW I made a diagram explaining what is going on, that I wanted to share even though I am not sure it belongs in the comments directly: ``` Query: SELECT t.a FROM t WHERE t.b > 5 ┌────────────────────┐ │ Projection(t.a) │ └────────────────────┘ ▲ │ │ ┌────────────────────┐ Filter ┌────────────────────┐ Projection ┌────────────────────┐ │ Filter(t.b > 5) │ ────Pushdown──▶ │ Projection(t.a) │ ────Pushdown──▶ │ Projection(t.a) │ └────────────────────┘ └────────────────────┘ └────────────────────┘ ▲ ▲ ▲ │ │ │ │ │ │ ┌────────────────────┐ ┌────────────────────┐ ┌────────────────────┐ │ Scan │ │ Scan │ │ Scan │ └────────────────────┘ │ filter=(t.b > 5) │ │ filter=(t.b > 5) │ └────────────────────┘ │ projection=(t.a) │ └────────────────────┘ Initial Plan Projection pushdown notes that If `TableProviderFilterPushDown` the scan only needs t.a returns true, filter pushdown pushes the filter into the scan BUT internally evaluating the predicate still requires t.b ``` ## Are these changes tested? <!-- 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? <!-- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
