2010YOUY01 commented on code in PR #25564:
URL: https://github.com/apache/datafusion/pull/25564#discussion_r4068407107
##########
datafusion/physical-plan/src/aggregates/mod.rs:
##########
@@ -905,49 +900,74 @@ pub struct AggregateExec {
}
impl AggregateExec {
+ /// Try to stop after enough distinct grouping keys have been accumulated.
+ ///
+ /// The caller must establish that discarding other groups is legal, for
+ /// example beneath `SELECT DISTINCT k FROM t LIMIT 10`. The parent limit
+ /// remains responsible for enforcing the exact number of rows.
+ ///
+ /// # Trigger conditions
+ ///
+ /// - Grouping with no aggregate expressions or aggregate filters.
+ /// - Ordering eligible under
[`Self::is_unordered_unfiltered_group_by_distinct`],
+ /// including no existing Top-K direction.
+ /// - A positive limit that is tighter than any existing limit.
+ ///
+ /// # Consistency
+ ///
+ /// This is a safe, atomic optimization: it preserves the grouping keys and
+ /// leaves the aggregate in a consistent state. Inapplicable requests are
+ /// no-ops; the existing configuration is returned unchanged.
+ pub fn try_optimize_distinct_soft_limit(
+ mut self,
+ limit: usize,
+ ) -> Result<Transformed<Self>> {
+ if limit == 0
Review Comment:
Updated in
[2cf27d8](https://github.com/apache/datafusion/pull/25564/commits/2cf27d8e1022d765d46548ac4260ce1b16eb9ef1)
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