github-actions[bot] commented on code in PR #64330:
URL: https://github.com/apache/doris/pull/64330#discussion_r3385788040
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fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/PullUpProjectExprUnderTopN.java:
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@@ -244,6 +244,13 @@ private static void collectFromNode(Plan node, PullUpInfo
info, Set<ExprId> bloc
for (NamedExpression ne : project.getProjects()) {
if (canPullUp(ne) && !blockedExprIds.contains(ne.getExprId()))
{
info.addPulledUpExpr(project, ne);
+ } else if (ne instanceof Alias && ne.child(0) instanceof Slot)
{
+ // Chain: this intermediate project renames a slot that may
+ // come from a pulled-up expression deeper in the tree.
+ // Register Slot(alias.toSlot()) → child Slot so that
+ // getPullUpReplaceExpression can resolve the chain later.
+ context.pullUpExprReplaceMap.putIfAbsent(ne.toSlot(),
ne.child(0));
+ blockedExprIds.add(((Slot) ne.child(0)).getExprId());
Review Comment:
This blocks the unblocked chain case that this PR is trying to enable. For
example, in `TopN(order by id) -> Project(y = x, id) -> Project(x = a + 1, id)
-> Scan`, `y` is not consumed by the TopN order key, so `x = a + 1` should
still be collected and restored above the TopN as the output for `y`. This
branch records `y -> x`, but then immediately adds `x` to `blockedExprIds`;
when the collector reaches the lower project, `x` is considered blocked,
`info.allPulledUpExprs` stays empty, and the rewrite returns the original plan.
The blocked-order-key case from the existing thread does need transitive
blocking, but it should propagate from aliases that are actually blocked, not
from every forwarding alias.
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