Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/7813#discussion_r36053152
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/SortBasedAggregationIterator.scala
---
@@ -0,0 +1,240 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution.aggregate
+
+import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.catalyst.expressions._
+import
org.apache.spark.sql.catalyst.expressions.aggregate.{AggregateExpression2,
AggregateFunction2}
+import org.apache.spark.sql.execution.UnsafeFixedWidthAggregationMap
+import org.apache.spark.sql.types.StructType
+import org.apache.spark.unsafe.KVIterator
+
+/**
+ * An iterator used to evaluate [[AggregateFunction2]]. It assumes the
input rows are sorted
+ * by values of [[groupingKeyAttributes]].
+ */
+class SortBasedAggregationIterator(
+ groupingKeyAttributes: Seq[Attribute],
+ valueAttributes: Seq[Attribute],
+ inputKVIterator: KVIterator[InternalRow, InternalRow],
+ nonCompleteAggregateExpressions: Seq[AggregateExpression2],
+ nonCompleteAggregateAttributes: Seq[Attribute],
+ completeAggregateExpressions: Seq[AggregateExpression2],
+ completeAggregateAttributes: Seq[Attribute],
+ initialInputBufferOffset: Int,
+ resultExpressions: Seq[NamedExpression],
+ newMutableProjection: (Seq[Expression], Seq[Attribute]) => (() =>
MutableProjection),
+ outputsUnsafeRows: Boolean)
+ extends AggregationIterator(
+ groupingKeyAttributes,
+ valueAttributes,
+ nonCompleteAggregateExpressions,
+ nonCompleteAggregateAttributes,
+ completeAggregateExpressions,
+ completeAggregateAttributes,
+ initialInputBufferOffset,
+ resultExpressions,
+ newMutableProjection,
+ outputsUnsafeRows) {
+
+ logInfo(s"Using SortBasedAggregationIterator (output UnsafeRow:
$outputsUnsafeRows).")
+
+ override protected def newBuffer: MutableRow = {
+ val bufferSchema = allAggregateFunctions.flatMap(_.bufferAttributes)
+ val bufferRowSize: Int = bufferSchema.length
+
+ val genericMutableBuffer = new GenericMutableRow(bufferRowSize)
+ val useUnsafeBuffer =
bufferSchema.map(_.dataType).forall(UnsafeRow.isFixedLength)
+
+ val buffer = if (useUnsafeBuffer) {
+ val unsafeProjection =
+ UnsafeProjection.create(bufferSchema.map(_.dataType))
+ unsafeProjection.apply(genericMutableBuffer)
+ } else {
+ genericMutableBuffer
+ }
+ initializeBuffer(buffer)
+ buffer
+ }
+
+
///////////////////////////////////////////////////////////////////////////
+ // Mutable states for sort based aggregation.
+
///////////////////////////////////////////////////////////////////////////
+
+ // The partition key of the current partition.
+ protected var currentGroupingKey: InternalRow = _
+
+ // The partition key of next partition.
+ protected var nextGroupingKey: InternalRow = _
+
+ // The first row of next partition.
+ protected var firstRowInNextGroup: InternalRow = _
+
+ // Indicates if we has new group of rows from the sorted input iterator
+ protected var sortedInputHasNewGroup: Boolean = false
+
+ // The aggregation buffer used by the sort-based aggregation.
+ protected val sortBasedAggregationBuffer: MutableRow = newBuffer
+
+ /** Processes rows in the current group. It will stop when it find a new
group. */
+ protected def processCurrentSortedGroup(): Unit = {
+ currentGroupingKey = nextGroupingKey
+ // Now, we will start to find all rows belonging to this group.
+ // We create a variable to track if we see the next group.
+ var findNextPartition = false
+ // firstRowInNextGroup is the first row of this group. We first
process it.
+ processRow(sortBasedAggregationBuffer, firstRowInNextGroup)
+
+ // The search will stop when we see the next group or there is no
+ // input row left in the iter.
+ var hasNext = inputKVIterator.next()
+ while (!findNextPartition && hasNext) {
+ // Get the grouping key.
+ val groupingKey = inputKVIterator.getKey
+ val currentRow = inputKVIterator.getValue
+
+ // Check if the current row belongs the current input row.
+ if (currentGroupingKey == groupingKey) {
+ processRow(sortBasedAggregationBuffer, currentRow)
+
+ hasNext = inputKVIterator.next()
+ } else {
+ // We find a new group.
+ findNextPartition = true
+ nextGroupingKey = groupingKey.copy()
+ firstRowInNextGroup = currentRow.copy()
+ }
+ }
+ // We have not seen a new group. It means that there is no new row in
the input
+ // iter. The current group is the last group of the iter.
+ if (!findNextPartition) {
+ sortedInputHasNewGroup = false
+ }
+ }
+
+
///////////////////////////////////////////////////////////////////////////
+ // Iterator's public methods
+
///////////////////////////////////////////////////////////////////////////
+
+ override final def hasNext: Boolean = sortedInputHasNewGroup
+
+ val toSafeResult =
FromUnsafeProjection(resultExpressions.map(_.dataType).toArray)
--- End diff --
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