raghavyadav01 commented on code in PR #26874:
URL: https://github.com/apache/datafusion/pull/26874#discussion_r4505047939
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datafusion/optimizer/src/decorrelate_lateral_join.rs:
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@@ -88,6 +88,21 @@ fn rewrite_internal(join: Join) ->
Result<Transformed<LogicalPlan>> {
let subquery_plan = subquery.subquery.as_ref();
let original_join_filter = join.filter.clone();
+ // A HAVING over an ungrouped aggregate can remove the aggregate's only
+ // row. The rewrite below handles neither case correctly, so leave the join
+ // correlated and let the query error instead of returning wrong rows.
+ // <https://github.com/apache/datafusion/issues/21198>
+ // - An inner lateral join becomes an outer join that keeps every outer
row,
+ // so an outer row whose row the HAVING removes comes back with NULLs.
+ // - A HAVING that reads an outer column is moved into the join condition,
+ // where the count bug handling turns its unmatched rows into a count of
0,
+ // for a left lateral join too.
+ if let Some(having) = having_over_ungrouped_aggregate(subquery_plan)
Review Comment:
Thanks @jayzhan211, good catch. Applied the `pulled_up_scalar_agg` gate,
added both tests (they fail on the old head and pass now), and merged the two
`Filter` arms.
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