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https://issues.apache.org/jira/browse/FLINK-9715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16634006#comment-16634006
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ASF GitHub Bot commented on FLINK-9715:
---------------------------------------
twalthr commented on a change in pull request #6776: [FLINK-9715][table]
Support temporal join with event time
URL: https://github.com/apache/flink/pull/6776#discussion_r221586412
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/join/TemporalRowtimeJoin.scala
##########
@@ -0,0 +1,307 @@
+/*
+ * 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.flink.table.runtime.join
+
+import java.lang.{Long => JLong}
+import java.util
+import java.util.Comparator
+
+import org.apache.flink.api.common.functions.FlatJoinFunction
+import org.apache.flink.api.common.state._
+import org.apache.flink.api.common.typeinfo.{BasicTypeInfo, TypeInformation}
+import org.apache.flink.runtime.state.{VoidNamespace, VoidNamespaceSerializer}
+import org.apache.flink.streaming.api.SimpleTimerService
+import org.apache.flink.streaming.api.operators._
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord
+import org.apache.flink.table.api.{StreamQueryConfig, TableException}
+import org.apache.flink.table.codegen.Compiler
+import org.apache.flink.table.runtime.CRowWrappingCollector
+import org.apache.flink.table.runtime.types.CRow
+import org.apache.flink.table.typeutils.TypeCheckUtils._
+import org.apache.flink.table.util.Logging
+import org.apache.flink.types.Row
+
+import scala.collection.JavaConversions._
+
+/**
+ * This operator works by keeping on the state collection of probe and build
records to process
+ * on next watermark. The idea is that between watermarks we are collecting
those elements
+ * and once we are sure that there will be no updates we emit the correct
result and clean up the
+ * state.
+ *
+ * Cleaning up the state drops all of the "old" values from the probe side,
where "old" is defined
+ * as older then the current watermark. Build side is also cleaned up in the
similar fashion,
+ * however we always keep at least one record - the latest one - even if it's
past the last
+ * watermark.
+ *
+ * One more trick is how the emitting results and cleaning up is triggered.
It is achieved
+ * by registering timers for the keys. We could register a timer for every
probe and build
+ * side element's event time (when watermark exceeds this timer, that's when
we are emitting and/or
+ * cleaning up the state). However this would cause huge number of registered
timers. For example
+ * with following evenTimes of probe records accumulated: {1, 2, 5, 8, 9}, if
we
+ * had received Watermark(10), it would trigger 5 separate timers for the
same key. To avoid that
+ * we always keep only one single registered timer for any given key,
registered for the minimal
+ * value. Upon triggering it, we process all records with event times older
then currentWatermark.
+ */
+class TemporalRowtimeJoin(
+ leftType: TypeInformation[Row],
+ rightType: TypeInformation[Row],
+ genJoinFuncName: String,
+ genJoinFuncCode: String,
+ queryConfig: StreamQueryConfig,
+ leftTimeAttribute: Int,
+ rightTimeAttribute: Int)
+ extends AbstractStreamOperator[CRow]
+ with TwoInputStreamOperator[CRow, CRow, CRow]
+ with Triggerable[Any, VoidNamespace]
+ with Compiler[FlatJoinFunction[Row, Row, Row]]
+ with Logging {
+
+ validateEqualsHashCode("join", leftType)
+ validateEqualsHashCode("join", rightType)
+
+ private val netLeftIndexStateName = "next-index"
+ private val leftStateName = "left"
+ private val rightStateName = "right"
+ private val registeredTimerStateName = "timer"
+ private val probteTimersStateName = "probe-timers"
+
+ private val rightRowtimeComparator = new
RowtimeComparator(rightTimeAttribute)
+
+ /**
+ * Incremental index generator for `leftState`'s keys.
+ */
+ private var nextLeftIndex: ValueState[JLong] = _
+
+ /**
+ * This could have been a MultiMap indexed by rowtime, but we have to
handle rows with
+ * duplicated rowtimes. We can not use List, because we need efficient
deletes of the oldest
+ * rows.
+ *
+ * TODO: this could be OrderedMultiMap[Jlong, Row] indexed by row's
timestamp, to avoid
+ * full map traversals (if we have lots of rows on the state that exceed
`currentWatermark`).
+ */
+ private var leftState: MapState[JLong, Row] = _
+
+ /**
+ * TODO: having `rightState` as an OrderedMapState would allow us to avoid
sorting cost
+ * once per watermark
+ */
+ private var rightState: MapState[JLong, Row] = _
+
+ private var registeredTimer: ValueState[JLong] = _ // JLong for correct
handling of default null
+
+ private var cRowWrapper: CRowWrappingCollector = _
+ private var collector: TimestampedCollector[CRow] = _
+ private var timerService: SimpleTimerService = _
+
+ private var joinFunction: FlatJoinFunction[Row, Row, Row] = _
+
+ override def open(): Unit = {
+ val clazz = compile(
+ getRuntimeContext.getUserCodeClassLoader,
+ genJoinFuncName,
+ genJoinFuncCode)
+
+ joinFunction = clazz.newInstance()
+
+ nextLeftIndex = getRuntimeContext.getState(
+ new ValueStateDescriptor[JLong](netLeftIndexStateName,
BasicTypeInfo.LONG_TYPE_INFO))
+ leftState = getRuntimeContext.getMapState(
+ new MapStateDescriptor[JLong, Row](leftStateName,
BasicTypeInfo.LONG_TYPE_INFO, leftType))
+ rightState = getRuntimeContext.getMapState(
+ new MapStateDescriptor[JLong, Row](rightStateName,
BasicTypeInfo.LONG_TYPE_INFO, rightType))
+ registeredTimer = getRuntimeContext.getState(
+ new ValueStateDescriptor[JLong](registeredTimerStateName,
BasicTypeInfo.LONG_TYPE_INFO))
+
+ collector = new TimestampedCollector[CRow](output)
+ cRowWrapper = new CRowWrappingCollector()
+ cRowWrapper.out = collector
+
+ val internalTimerService = getInternalTimerService(
+ probteTimersStateName,
+ VoidNamespaceSerializer.INSTANCE,
+ this)
+
+ timerService = new SimpleTimerService(internalTimerService)
+ }
+
+ override def processElement1(element: StreamRecord[CRow]): Unit = {
+ if (!element.getValue.change) {
+ throw new TableException(
+ s"${classOf[TemporalRowtimeJoin].getSimpleName} does not support
retractions on the " +
+ s"left side.")
+ }
+
+ leftState.put(getNextLeftIndex, element.getValue.row)
+ maybeRegisterTimer(getLeftTime(element.getValue.row)) // Timer to emit and
clean up the state
+ }
+
+ override def processElement2(element: StreamRecord[CRow]): Unit = {
+ if (!element.getValue.change) {
+ throw new TableException(
+ s"${classOf[TemporalRowtimeJoin].getSimpleName} does not support
retractions on the" +
+ s"right side.")
+ }
+
+ val rowTime = getRightTime(element.getValue.row)
+ rightState.put(rowTime, element.getValue.row)
+ maybeRegisterTimer(rowTime) // Timer to clean up the state
+ }
+
+ private def maybeRegisterTimer(timestamp: Long): Unit = {
+ val currentRegisteredTimer = registeredTimer.value()
+ if (currentRegisteredTimer == null) {
+ registerTimer(timestamp)
+ }
+ else if (currentRegisteredTimer != null && currentRegisteredTimer >
timestamp) {
+ timerService.deleteEventTimeTimer(currentRegisteredTimer)
+ registerTimer(timestamp)
+ }
+ }
+
+ private def registerTimer(timestamp: Long): Unit = {
+ registeredTimer.update(timestamp)
+ timerService.registerEventTimeTimer(timestamp)
+ }
+
+ override def onProcessingTime(timer: InternalTimer[Any, VoidNamespace]):
Unit = {
+ throw new IllegalStateException("This should never happen")
+ }
+
+ override def onEventTime(timer: InternalTimer[Any, VoidNamespace]): Unit = {
+ registeredTimer.clear()
+ val lastUnprocessedTime =
emitResultAndCleanUpState(timerService.currentWatermark())
+ lastUnprocessedTime.foreach(registerTimer)
+ }
+
+ /**
+ * @return a row time of the oldest unprocessed probe record or None, if
all records have been
+ * processed.
+ */
+ private def emitResultAndCleanUpState(timerTimestamp: Long): Option[Long] = {
+ val rightRowsSorted = getRightRowsSorted(rightRowtimeComparator)
+ var lastUnprocessedTime: Option[Long] = None
+
+ val leftIterator = leftState.entries().iterator()
+ while (leftIterator.hasNext) {
+ val leftEntry = leftIterator.next()
+ val leftRow = leftEntry.getValue
+ val leftTime = getLeftTime(leftRow)
+
+ if (leftTime <= timerTimestamp) {
+ val rightRowIndex = latestRightRowToJoin(rightRowsSorted, leftTime)
+
+ if (rightRowIndex >= 0) {
+ val rightRow = rightRowsSorted.get(rightRowIndex)
+
+ cRowWrapper.setChange(true)
+ collector.setAbsoluteTimestamp(leftTime)
+ joinFunction.join(leftRow, rightRow, cRowWrapper)
+ }
+ leftIterator.remove()
+ }
+ else {
+ lastUnprocessedTime = Some(
+ Math.min(
+ lastUnprocessedTime.getOrElse(Long.MaxValue),
+ leftTime))
+ }
+ }
+
+ // remove all right entries older then the watermark, except the latest one
+ // for example with rightState = [1, 5, 9] and watermark = 6
+ // we can not remove "5" from rightState, because left elements with
rowtime of 7 or 8
+ // could be joined with it later
+ rightRowsSorted.map(rightRow => getRightTime(rightRow))
Review comment:
Use plain old Java (while loops in Scala) for this logic. Scala might
introduce a lot of helper methods/helper objects etc. We should be in control
how this is executed.
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> Support versioned joins with event time
> ---------------------------------------
>
> Key: FLINK-9715
> URL: https://issues.apache.org/jira/browse/FLINK-9715
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Affects Versions: 1.5.0
> Reporter: Piotr Nowojski
> Assignee: Piotr Nowojski
> Priority: Major
> Labels: pull-request-available
>
> Queries like:
> {code:java}
> SELECT
> o.amount * r.rate
> FROM
> Orders AS o,
> LATERAL TABLE (Rates(o.rowtime)) AS r
> WHERE o.currency = r.currency{code}
> should work with event time
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