Phoenix500526 opened a new pull request, #23166:
URL: https://github.com/apache/datafusion/pull/23166
## Which issue does this PR close?
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- Closes #23159
## Rationale for this change
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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
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Join unparsing handles the left and right inputs inline in
`select_to_sql_recursively` (`datafusion/sql/src/unparser/plan.rs`). Both
sides
repeated the same table-scan filter extraction
(`try_transform_to_simple_table_scan_with_filters`: extend the collected
filters, then return the simplified or original plan), while the
passthrough-`Projection(Join)` handling intentionally diverges per side (the
left input can be unwrapped; the right input may need a nested-join relation
so
SQL preserves the required join grouping).
Centralizing only the duplicated common setup — and keeping the side-specific
behavior explicit — makes the two paths easier to read and keeps the
alias-scope invariant in one obvious place. #23159 tracks this.
## What changes are included in this PR?
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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.
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- Extract the duplicated filter-extraction dispatch into a small helper
`extract_join_input_table_scan_filters(plan, &mut table_scan_filters)`, and
call it from both the left and right join-input paths.
- Keep the side-specific passthrough-projection handling inline and explicit
(left: `unwrap_qualified_passthrough_join_projection`; right:
`qualified_passthrough_join_projection_to_nested_relation`).
- Tests: factor the shared three-table setup into a
`nested_passthrough_join_tables()` helper, and add
`test_unparse_projected_join_unwraps_left_nested_passthrough_projection` to
mirror the existing right-input test (this also fills a left-side coverage
gap).
This is a pure refactor with no behavior change.
## Are these changes tested?
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Covered by existing tests plus the new left-input test, all passing:
- `cargo test -p datafusion-sql --test sql_integration`
(includes both `..._left_..._passthrough_projection` and
`..._right_..._passthrough_projection`)
- `cargo clippy -p datafusion-sql --tests -- -D warnings`
- `cargo fmt --all`
Existing inline snapshots are unchanged (no behavior change); the new test
locks
in the left-input behavior the refactor touches.
## Are there any user-facing changes?
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updated before approving the PR.
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No. This is an internal refactor of the SQL unparser; the generated SQL is
unchanged and there are no public API changes.
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