zhuqi-lucas commented on code in PR #22612:
URL: https://github.com/apache/datafusion/pull/22612#discussion_r3330243618
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datafusion/optimizer/src/eliminate_cross_join.rs:
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@@ -207,6 +218,62 @@ impl OptimizerRule for EliminateCrossJoin {
}
}
+/// Returns `true` if `plan` contains at least one [`LogicalPlan::Join`]
+/// node, either directly in its tree *or* inside an embedded subquery
+/// plan reachable through `Expr::ScalarSubquery` / `Expr::InSubquery`
+/// / `Expr::Exists` / `Expr::SetComparison`.
+///
+/// Used as a fast-path gate at the top of [`EliminateCrossJoin::rewrite`]
+/// so that join-free plans skip the full recursive rewrite. The
+/// expression-side recursion is required because `rewrite_children`
+/// also dives into uncorrelated subqueries via
+/// `map_uncorrelated_subqueries`; ignoring them here would skip
+/// optimizing a `CROSS JOIN` that sits only inside an
+/// `IN (SELECT ... FROM a, b)`-style predicate.
+///
+/// Read-only `apply` walk with early stop on first match, no
+/// allocations.
+fn plan_has_joins(plan: &LogicalPlan) -> bool {
+ let mut found = false;
+ let _ = plan.apply(|node| {
+ if matches!(node, LogicalPlan::Join(_)) {
+ found = true;
+ return Ok(TreeNodeRecursion::Stop);
+ }
+ // Recurse into subquery plans referenced from this node's
+ // expressions. `LogicalPlan::apply` does not descend into the
+ // subquery plan, so we have to do it explicitly.
+ let _ = node.apply_expressions(|expr| {
+ if found {
+ return Ok(TreeNodeRecursion::Stop);
+ }
+ let _ = expr.apply(|e| {
Review Comment:
Thanks @alamb , `apply_with_subqueries` is exactly what I needed.
Addressed in latest PR!
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