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branch-4.2: [fix](local shuffle) Require hash input for distinct finalize agg without group keys #66570 #68190

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branch-4.2: [fix](local shuffle) Require hash input for distinct finalize agg without group keys #66570 #68190

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75 changes: 55 additions & 20 deletions fe/fe-core/src/main/java/org/apache/doris/planner/AggregationNode.java
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Original file line number Diff line number Diff line change
Expand Up @@ -302,6 +302,8 @@ public Pair<PlanNode, LocalExchangeType> enforceAndDeriveLocalExchange(
// PR #62438: when false, non-finalize agg falls back to BE base class.
boolean enableLeBeforeAgg = sessionVariable.enableLocalExchangeBeforeAgg;
boolean hasKeys = !aggInfo.getGroupingExprs().isEmpty();
boolean selfOrInheritedShuffled = translatorContext.hasShuffleForCorrectnessAncestor(this)
|| requiresShuffleForCorrectness();

// Each branch mirrors the corresponding BE operator's required_data_distribution()
// check order 1:1. The helper baseClassRequire() expands BE's base class behavior.
Expand Down Expand Up @@ -355,7 +357,16 @@ public Pair<PlanNode, LocalExchangeType> enforceAndDeriveLocalExchange(
// early return also catches FIRST_MERGE, dropping the HASH requirement and
// causing wrong-result (e.g. PASSTHROUGH over serial child breaks the
// group-by-key invariant — DORIS-25413).
if (!hasKeys) {
if (!hasPartitionRequirement(selfOrInheritedShuffled)) {
// No effective partition key (no group keys, and no child distribute
// exprs set for a DISTINCT / followed-by-shuffle agg): the input
// distribution is irrelevant. A finalize agg with an effective key
// emits per-instance scalar values (sum0(multi_distinct_count(...))
// above) that the parent sums, so same-key rows must stay in a single
// instance — this mirrors BE's `_partition_exprs` exactly, and keeps
// a directly called multi_distinct_count(col) (no distribute exprs)
// on the no-requirement path instead of collapsing it onto a zero-key
// HASH exchange.
requireChild = needsFinalize
? LocalExchangeTypeRequire.noRequire()
: baseClassRequire(connectContext);
Expand All @@ -368,13 +379,16 @@ public Pair<PlanNode, LocalExchangeType> enforceAndDeriveLocalExchange(
// FIRST_MERGE (correctness) or finalize+colocate → HASH.
requireChild = parentRequire.autoRequireHash();
} else if (hasPartitionExprs(parentRequire)) {
// FE-only heuristic: finalize non-colocate with parent hash requirement
// → inherit parent's specific hash type.
// finalize non-colocate with a parent hash requirement → inherit the
// parent's specific hash type.
requireChild = parentRequire.autoRequireHash();
} else {
// FE-only heuristic: finalize non-colocate without parent hash → skip
// LE (child Exchange already provides hash distribution).
requireChild = LocalExchangeTypeRequire.noRequire();
// finalize non-colocate without a parent hash requirement: the input
// must still be key-aligned (group/distinct key), so require HASH
// explicitly instead of trusting the child's distribution. When the
// child already provides hash distribution, satisfy() passes and no
// LE is inserted, so this is safe and free in the common case.
requireChild = LocalExchangeTypeRequire.requireHash();
}
}

Expand All @@ -391,6 +405,34 @@ private LocalExchangeTypeRequire baseClassRequire(ConnectContext connectContext)
: LocalExchangeTypeRequire.noRequire();
}

/**
* Whether this agg needs key-aligned (hash-partitioned) input from its child.
* Mirrors BE AggSinkOperatorX::update_operator's `_partition_exprs` exactly:
* non-empty grouping exprs, or the child distribute exprs when the plan set
* them for a DISTINCT (or followed-by-shuffle) agg. The test is on the
* *effective* key, not the function name: a directly called
* multi_distinct_count(col) has neither distribute exprs nor grouping exprs,
* so it stays on the no-requirement path — a zero-key HASH exchange would
* collapse the whole input onto one task per BE. A finalize agg with an
* effective key emits per-instance scalar values (the
* sum0(multi_distinct_count(...)) above) that the parent sums, so same-key
* rows must stay in a single instance.
*/
private boolean hasPartitionRequirement(boolean followedByShuffled) {
return !getLocalExchangeDistributeExprs(0, followedByShuffled).isEmpty();
}

private boolean hasDistinctAggregate() {
// Multi-distinct aggregates are detected by function name. Nereids rewrites
// count/sum/group_concat(distinct ...) into dedicated MultiDistinct* functions
// constructed with distinct=false, so by this legacy FunctionCallExpr layer
// isDistinct() is already false and the function name is the only signal.
return aggInfo.getAggregateExprs().stream()
.map(FunctionCallExpr::getFnName)
.map(name -> name.getFunction())
.anyMatch(name -> name.startsWith("multi_distinct_"));
}

@Override
protected List<Expr> getSemanticPartitionExprs() {
return aggInfo.getGroupingExprs();
Expand All @@ -406,18 +448,7 @@ protected List<Expr> getLocalExchangeDistributeExprs(int childIndex, boolean fol
// chain scatters same-group rows across N instances, leaving partial_preagg essentially a
// no-op and breaking row-arrival order at downstream merge-finalize (e.g. group_concat).
List<Expr> childDist = getChildDistributeExprList(childIndex);
// Multi-distinct aggregates are detected by function name. Nereids rewrites
// count/sum(distinct ...) into dedicated MultiDistinct* functions constructed with
// distinct=false and a "multi_distinct_" name, so by this legacy FunctionCallExpr layer
// isDistinct() is already false and the function name is the only remaining signal —
// there is no structural flag to test here.
boolean hasDistinct = aggInfo.getAggregateExprs().stream()
.map(FunctionCallExpr::getFnName)
.filter(name -> name != null)
.map(name -> name.getFunction())
.filter(name -> name != null)
.anyMatch(name -> name.startsWith("multi_distinct_"));
if (childDist != null && !childDist.isEmpty() && (followedByShuffled || hasDistinct)) {
if (childDist != null && !childDist.isEmpty() && (followedByShuffled || hasDistinctAggregate())) {
return childDist;
}
return Lists.newArrayList(aggInfo.getGroupingExprs());
Expand All @@ -426,13 +457,17 @@ protected List<Expr> getLocalExchangeDistributeExprs(int childIndex, boolean fol
@Override
public boolean requiresShuffleForCorrectness() {
// Mirrors BE's AggSinkOperatorX::is_shuffled_operator() exactly:
// finalize agg with group keys needs hash-distributed input for correctness.
// finalize agg with partition exprs (group keys, or child distribute
// exprs set for a DISTINCT aggregate) needs hash-distributed input for
// correctness. The effective-key test is the node's own requirement
// (followedByShuffled=false); inherited shuffle state is added by the
// caller via selfOrInheritedShuffled.
// GLOBAL dedup (!needsFinalize) is intentionally NOT included here — if a
// GLOBAL dedup exists, a finalize agg always sits above it (e.g. DISTINCT_GLOBAL
// above DISTINCT_LOCAL/GLOBAL_DEDUP), and the finalize agg propagates the flag
// down via inheritedShuffled. A solo finalize agg satisfies hash distribution
// through its own child requirement.
return needsFinalize && !aggInfo.getGroupingExprs().isEmpty();
return needsFinalize && !getLocalExchangeDistributeExprs(0, false).isEmpty();
}

private boolean canUseDistinctStreamingAgg(SessionVariable sessionVariable) {
Expand Down
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