sigmod commented on code in PR #55629:
URL: https://github.com/apache/spark/pull/55629#discussion_r3184211391
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala:
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@@ -657,6 +657,34 @@ trait CheckAnalysis extends LookupCatalog with
QueryErrorsBase with PlanToString
messageParameters = Map.empty)
}
+ // Reject streaming inputs early. The optimizer rewrite groups by a
`__qid` derived
+ // from `MonotonicallyIncreasingID()` and feeds it to a global
`Aggregate`, which
+ // Spark turns into a stateful streaming aggregation. Because MID
restarts per
+ // micro-batch, `__qid` values collide across batches, and the
stateful aggregate
+ // silently merges state from old batches into new rows that share
the same key --
+ // producing wrong top-K results. Failing at analysis time is
clearer than letting
+ // this slip through. Streaming support is tracked as a follow-up;
resolving it does
+ // not require streaming-aware MID and is likely to come from a
different grouping
+ // strategy or a dedicated physical operator.
+ case j: NearestByJoin if j.isStreaming =>
+ j.failAnalysis(
+ errorClass = "NEAREST_BY_JOIN.STREAMING_NOT_SUPPORTED",
+ messageParameters = Map.empty)
+
+ case j @ NearestByJoin(_, _, _, _, _, rankingExpression, _)
+ if !RowOrdering.isOrderable(rankingExpression.dataType) =>
+ j.failAnalysis(
+ errorClass = "NEAREST_BY_JOIN.NON_ORDERABLE_RANKING_EXPRESSION",
+ messageParameters = Map(
+ "expression" -> toSQLExpr(rankingExpression),
+ "type" -> toSQLType(rankingExpression.dataType)))
+
+ case j @ NearestByJoin(_, _, _, false, _, rankingExpression, _)
+ if !rankingExpression.deterministic =>
+ j.failAnalysis(
Review Comment:
Do we have to fail this case?
We still call the result of the following query "exact results" rather than
"approximate results"?
> SELECT any_value(t.v)
> FROM t
I view them as
- exact results: can be deterministic or non-deterministic, but deliver a
well-defined semantics w.r.t. input/output.
- approx results: there's no well-defined semantics w.r.t. input/output
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