Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/12067#discussion_r59617422
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/TypedAggregateExpression.scala
---
@@ -19,133 +19,153 @@ package org.apache.spark.sql.execution.aggregate
import scala.language.existentials
-import org.apache.spark.internal.Logging
import org.apache.spark.sql.Encoder
-import org.apache.spark.sql.catalyst.InternalRow
-import org.apache.spark.sql.catalyst.encoders.{encoderFor,
ExpressionEncoder, OuterScopes}
+import org.apache.spark.sql.catalyst.analysis.{UnresolvedAttribute,
UnresolvedDeserializer, UnresolvedExtractValue}
+import org.apache.spark.sql.catalyst.encoders.encoderFor
import org.apache.spark.sql.catalyst.expressions._
-import
org.apache.spark.sql.catalyst.expressions.aggregate.ImperativeAggregate
+import
org.apache.spark.sql.catalyst.expressions.aggregate.DeclarativeAggregate
import org.apache.spark.sql.expressions.Aggregator
import org.apache.spark.sql.types._
object TypedAggregateExpression {
- def apply[A, B : Encoder, C : Encoder](
- aggregator: Aggregator[A, B, C]): TypedAggregateExpression = {
+ def apply[BUF : Encoder, OUT : Encoder](
+ aggregator: Aggregator[_, BUF, OUT]): TypedAggregateExpression = {
+ val bufferEncoder = encoderFor[BUF]
+ // We will insert the deserializer and function call expression at the
bottom of each serializer
+ // expression while executing `TypedAggregateExpression`, which means
multiply serializer
+ // expressions will all evaluate the same sub-expression at bottom.
To avoid the re-evaluating,
+ // here we always use one single serializer expression to serialize
the buffer object into a
+ // single-field row, no matter whether the encoder is flat or not. We
also need to update the
+ // deserializer to read in all fields from that single-field row.
+ // TODO: remove this trick after we have better integration of
subexpression elimination and
--- End diff --
Can we hold this pr a little bit? let me think of how to do subexpression
elimination in aggregate.
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