uros-b commented on code in PR #58119:
URL: https://github.com/apache/spark/pull/58119#discussion_r3862336331
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/RewriteWithExpression.scala:
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@@ -66,6 +66,23 @@ object RewriteWithExpression extends Rule[LogicalPlan] {
}
}
+ /**
+ * Rewrites the `With` expressions in a single expression tree by inlining
their common
+ * expressions. Uses `transformUp` to handle nested `With`.
+ *
+ * Does not descend into subquery plans (e.g. `ScalarSubquery`). A caller
whose expression
+ * may contain a subquery must rewrite those plans separately.
+ */
+ def applyForExpression(expression: Expression): Expression = {
+ expression.transformUpWithPruning(_.containsPattern(WITH_EXPRESSION)) {
+ case With(child, defs) =>
+ val refToExpr = defs.map(commonExprDef => commonExprDef.id ->
commonExprDef.child).toMap
+ child.transformWithPruning(_.containsPattern(COMMON_EXPR_REF)) {
+ case ref: CommonExpressionRef if refToExpr.contains(ref.id) =>
refToExpr(ref.id)
+ }
+ }
+ }
Review Comment:
applyForExpression duplicates every With definition, violating its
evaluate-once contract for non-foldable/stateful expressions. Procedure
arguments are foldable, so the intended caller is safe, but that precondition
is neither enforced nor documented. Restrict the helper to foldable definitions
or reject unsupported expressions.
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