cloud-fan commented on a change in pull request #20965: [SPARK-21870][SQL]
Split aggregation code into small functions
URL: https://github.com/apache/spark/pull/20965#discussion_r318525635
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/HashAggregateExec.scala
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@@ -255,41 +260,148 @@ case class HashAggregateExec(
""".stripMargin
}
+ // Splits aggregate code into small functions because the most of JVM
implementations
+ // can not compile too long functions.
+ //
+ // Note: The difference from `CodeGenerator.splitExpressions` is that we
define an individual
+ // function for each aggregation function (e.g., SUM and AVG). For example,
in a query
+ // `SELECT SUM(a), AVG(a) FROM VALUES(1) t(a)`, we define two functions
+ // for `SUM(a)` and `AVG(a)`.
+ private def splitAggregateExpressions(
+ ctx: CodegenContext,
+ aggNames: Seq[String],
+ aggExprs: Seq[Seq[Expression]],
Review comment:
I have problems to understand this `aggExprs`, why it's a seq of seq?
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