Cheng Su created SPARK-34253:
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Summary: Object hash aggregate should not fallback if no more
input rows
Key: SPARK-34253
URL: https://issues.apache.org/jira/browse/SPARK-34253
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 3.2.0
Reporter: Cheng Su
Object hash aggregate will fallback to sort-based aggregation based on number
of keys seen so far [0]. The default config threshold is 128
(spark.sql.objectHashAggregate.sortBased.fallbackThreshold in [1]). There's an
edge case we can do better, where we do not fallback if there's no more input
rows. Suppose the task only has 128 group-by keys in hash ma, we don't need to
fallback in this case, and we can save the extra sort.
[0]:
[https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/ObjectAggregationIterator.scala#L161]
[1]:
[https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala#L1615]
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