[QECO-1569] Preserve projected constants in aggregate arguments - #24005
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Adam-Alani wants to merge 1 commit into
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[QECO-1569] Preserve projected constants in aggregate arguments#24005Adam-Alani wants to merge 1 commit into
Adam-Alani wants to merge 1 commit into
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Preserve column-free constants through projection and alias boundaries so aggregate arguments can be simplified without accepting row-varying columns.
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Why
Aggregate arguments that are constant can lose that property when a subquery or CTE projects them as columns.
approx_percentile_contthen rejects a projected literal because its accumulator cannot evaluate the physical column without input, even though the defining expression is query-global and constant.What
This preserves column-free, non-volatile aggregate arguments through projection and subquery-alias boundaries so normal expression simplification can evaluate them before physical planning. Row-varying columns remain unchanged and continue to be rejected by percentile validation.
How
The simplify-expressions rule collects safe constant definitions from projection chains, remaps them through subquery aliases, and substitutes only matching aggregate-expression columns while preserving output names. Scalar subqueries, volatile expressions, and expressions with column dependencies are excluded.
Validated with:
cargo test --test sqllogictests -p datafusion-sqllogictest -- aggregate.sltcargo test -p datafusion-optimizer simplify_expressions::simplify_exprscargo clippy -p datafusion-optimizer --all-features -- -D warningscargo fmt --all -- --checkCompanion to #23997; the PRs are independent and can merge in either order.