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/*
* 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.joins
import java.util.NoSuchElementException
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.execution.SparkPlan
import org.apache.spark.sql.execution.metric.LongSQLMetric
import org.apache.spark.sql.types.{IntegralType, LongType}
trait HashJoin {
self: SparkPlan =>
val leftKeys: Seq[Expression]
val rightKeys: Seq[Expression]
val buildSide: BuildSide
val condition: Option[Expression]
val left: SparkPlan
val right: SparkPlan
protected lazy val (buildPlan, streamedPlan) = buildSide match {
case BuildLeft => (left, right)
case BuildRight => (right, left)
}
protected lazy val (buildKeys, streamedKeys) = buildSide match {
case BuildLeft => (leftKeys, rightKeys)
case BuildRight => (rightKeys, leftKeys)
}
override def output: Seq[Attribute] = left.output ++ right.output
/**
* Try to rewrite the key as LongType so we can use getLong(), if they key can fit with a long.
*
* If not, returns the original expressions.
*/
def rewriteKeyExpr(keys: Seq[Expression]): Seq[Expression] = {
var keyExpr: Expression = null
var width = 0
keys.foreach { e =>
e.dataType match {
case dt: IntegralType if dt.defaultSize <= 8 - width =>
if (width == 0) {
if (e.dataType != LongType) {
keyExpr = Cast(e, LongType)
} else {
keyExpr = e
}
width = dt.defaultSize
} else {
val bits = dt.defaultSize * 8
keyExpr = BitwiseOr(ShiftLeft(keyExpr, Literal(bits)),
BitwiseAnd(Cast(e, LongType), Literal((1L << bits) - 1)))
width -= bits
}
// TODO: support BooleanType, DateType and TimestampType
case other =>
return keys
}
}
keyExpr :: Nil
}
protected val canJoinKeyFitWithinLong: Boolean = {
val sameTypes = buildKeys.map(_.dataType) == streamedKeys.map(_.dataType)
val key = rewriteKeyExpr(buildKeys)
sameTypes && key.length == 1 && key.head.dataType.isInstanceOf[LongType]
}
protected def buildSideKeyGenerator: Projection =
UnsafeProjection.create(rewriteKeyExpr(buildKeys), buildPlan.output)
protected def streamSideKeyGenerator: Projection =
UnsafeProjection.create(rewriteKeyExpr(streamedKeys), streamedPlan.output)
@transient private[this] lazy val boundCondition = if (condition.isDefined) {
newPredicate(condition.getOrElse(Literal(true)), left.output ++ right.output)
} else {
(r: InternalRow) => true
}
protected def hashJoin(
streamIter: Iterator[InternalRow],
numStreamRows: LongSQLMetric,
hashedRelation: HashedRelation,
numOutputRows: LongSQLMetric): Iterator[InternalRow] =
{
new Iterator[InternalRow] {
private[this] var currentStreamedRow: InternalRow = _
private[this] var currentHashMatches: Seq[InternalRow] = _
private[this] var currentMatchPosition: Int = -1
// Mutable per row objects.
private[this] val joinRow = new JoinedRow
private[this] val resultProjection: (InternalRow) => InternalRow =
UnsafeProjection.create(self.schema)
private[this] val joinKeys = streamSideKeyGenerator
override final def hasNext: Boolean = {
while (true) {
// check if it's end of current matches
if (currentHashMatches != null && currentMatchPosition == currentHashMatches.length) {
currentHashMatches = null
currentMatchPosition = -1
}
// find the next match
while (currentHashMatches == null && streamIter.hasNext) {
currentStreamedRow = streamIter.next()
numStreamRows += 1
val key = joinKeys(currentStreamedRow)
if (!key.anyNull) {
currentHashMatches = hashedRelation.get(key)
if (currentHashMatches != null) {
currentMatchPosition = 0
}
}
}
if (currentHashMatches == null) {
return false
}
// found some matches
buildSide match {
case BuildRight => joinRow(currentStreamedRow, currentHashMatches(currentMatchPosition))
case BuildLeft => joinRow(currentHashMatches(currentMatchPosition), currentStreamedRow)
}
if (boundCondition(joinRow)) {
return true
} else {
currentMatchPosition += 1
}
}
false // unreachable
}
override final def next(): InternalRow = {
// next() could be called without calling hasNext()
if (hasNext) {
currentMatchPosition += 1
numOutputRows += 1
resultProjection(joinRow)
} else {
throw new NoSuchElementException
}
}
}
}
}
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