github-actions[bot] commented on code in PR #67177:
URL: https://github.com/apache/doris/pull/67177#discussion_r3957298225
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fe/fe-core/src/main/java/org/apache/doris/planner/PlanNode.java:
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@@ -1109,6 +1117,18 @@ protected Pair<PlanNode, LocalExchangeType>
enforceRequire(
Pair<PlanNode, LocalExchangeType> childOutput =
child.enforceAndDeriveLocalExchange(translatorContext, this,
require);
+ // A serial consumer must not implicitly reduce a non-serial subtree
to one pipeline
+ // task. Besides losing parallelism, that can make a remote Exchange
expose fewer
+ // receiver tasks than FE addresses. Keep the subtree parallel and
make the N-to-one
+ // transition explicit. PASS_TO_ONE keeps every upstream receiver task
alive and
+ // funnels their output into the serial downstream pipeline's only
task.
+ if (passToOneAtSerialBoundary && childOutput.second !=
LocalExchangeType.PASS_TO_ONE) {
Review Comment:
[P1] Preserve this gather for unpartitioned analytic consumers
For a serial-source fragment, a reachable reduced tree is:
```text
AnalyticEval(OVER(), serial)
HashJoin(parallel)
...
Exchange / inner local exchange
```
This block correctly wraps the non-serial child in `PASS_TO_ONE`, but
`AnalyticEvalNode.enforceAndDeriveLocalExchange()` immediately unwraps every
returned `LocalExchangeNode` at lines 222-223. Because the new boundary logic
clears the serial markers while planning the child, inner exchanges can remain;
after the outer gather is removed, BE propagation can raise the analytic-sink
pipeline to N tasks while its paired serial analytic-source pipeline stays at
one task, recreating the shared-state/EOS mismatch this boundary is meant to
prevent. The changed no-partition unit fixture is fragment-less, so
`isSerialOperatorOnBe()` is false and it never exercises this case. Please
retain `PASS_TO_ONE` in the analytic special case and add a serial-source
analytic-over-parallel-subtree regression.
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