Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/4266#discussion_r127129047
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/join/WindowJoinUtil.scala
---
@@ -0,0 +1,349 @@
+/*
+ * 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.math.{BigDecimal => JBigDecimal}
+import java.util
+
+import org.apache.calcite.plan.RelOptUtil
+import org.apache.calcite.rel.`type`.RelDataType
+import org.apache.calcite.rel.core.JoinRelType
+import org.apache.calcite.rex._
+import org.apache.calcite.sql.SqlKind
+import org.apache.flink.api.common.functions.FlatJoinFunction
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.table.api.{TableConfig, TableException}
+import org.apache.flink.table.calcite.FlinkTypeFactory
+import org.apache.flink.table.codegen.{CodeGenerator, ExpressionReducer}
+import org.apache.flink.table.plan.schema.{RowSchema,
TimeIndicatorRelDataType}
+import org.apache.flink.types.Row
+
+import scala.collection.JavaConverters._
+
+/**
+ * An util class to help analyze and build join code .
+ */
+object WindowJoinUtil {
+
+ /**
+ * Analyze time-condtion to get time boundary for each stream and get
the time type
+ * and return remain condition.
+ *
+ * @param condition join condition
+ * @param leftLogicalFieldCnt left stream logical field num
+ * @param inputSchema join rowtype schema
+ * @param rexBuilder util to build rexNode
+ * @param config table environment config
+ * @return isRowTime, left lower boundary, right lower boundary, remain
condition
+ */
+ private[flink] def analyzeTimeBoundary(
+ condition: RexNode,
+ leftLogicalFieldCnt: Int,
+ inputSchema: RowSchema,
+ rexBuilder: RexBuilder,
+ config: TableConfig): (Boolean, Long, Long, Option[RexNode]) = {
+
+ // Converts the condition to conjunctive normal form (CNF)
+ val cnfCondition = RexUtil.toCnf(rexBuilder, condition)
+
+ // split the condition into time indicator condition and other
condition
+ val (timeTerms, remainTerms) = cnfCondition match {
+ case c: RexCall if cnfCondition.getKind == SqlKind.AND =>
+ c.getOperands.asScala
+ .map(analyzeCondtionTermType(_, leftLogicalFieldCnt,
inputSchema.logicalType))
+ .reduceLeft((l, r) => {
+ (l._1 ++ r._1, l._2 ++ r._2)
+ })
+ case _ =>
+ throw new TableException("A time-based stream join requires
exactly " +
+ "two join predicates that bound the time in both directions.")
+ }
+
+ if (timeTerms.size != 2) {
+ throw new TableException("A time-based stream join requires exactly
" +
+ "two join predicates that bound the time in both directions.")
+ }
+
+ // extract time offset from the time indicator conditon
+ val streamTimeOffsets =
+ timeTerms.map(x => extractTimeOffsetFromCondition(x._3, x._2,
rexBuilder, config))
+
+ val (leftLowerBound, leftUpperBound) =
+ streamTimeOffsets match {
+ case Seq((x, true), (y, false)) => (x, y)
+ case Seq((x, false), (y, true)) => (y, x)
+ case _ =>
+ throw new TableException(
+ "Time-based join conditions must reference the time attribute
of both input tables.")
+ }
+
+ // compose the remain condition list into one condition
+ val remainCondition =
+ remainTerms match {
+ case Seq() => None
+ case _ =>
+ // Converts logical field references to physical ones.
+ Some(remainTerms.map(inputSchema.mapRexNode).reduceLeft((l, r) => {
+ RelOptUtil.andJoinFilters(rexBuilder, l, r)
+ }))
+ }
+
+ val isRowTime: Boolean = timeTerms(0)._1 match {
+ case x if FlinkTypeFactory.isProctimeIndicatorType(x) => false
+ case _ => true
+ }
+ (isRowTime, leftLowerBound, leftUpperBound, remainCondition)
+ }
+
+ /**
+ * Split the join conditions into time condition and non-time condition
+ *
+ * @return (Seq(timeTerms), Seq(remainTerms)),
+ */
+ private def analyzeCondtionTermType(
+ conditionTerm: RexNode,
+ leftFieldCount: Int,
+ inputType: RelDataType): (Seq[(RelDataType, Boolean, RexNode)],
Seq[RexNode]) = {
+
+ conditionTerm match {
+ case c: RexCall if Seq(SqlKind.GREATER_THAN,
SqlKind.GREATER_THAN_OR_EQUAL,
+ SqlKind.LESS_THAN, SqlKind.LESS_THAN_OR_EQUAL).contains(c.getKind)
=>
+ val timeIndicators = extractTimeIndicatorAccesses(c,
leftFieldCount, inputType)
+ timeIndicators match {
+ case Seq() =>
+ (Seq(), Seq(c))
+ case Seq(v1, v2) =>
+ if (v1._1 != v2._1) {
+ throw new TableException(
+ "Both time attributes in a join condition must be of the
same type.")
+ }
+ if (v1._2 == v2._2) {
+ throw new TableException("Time-based join conditions " +
+ "must reference the time attribute of both input tables.")
+ }
+ (Seq((v1._1, v1._2, c)), Seq())
+ case _ =>
+ throw new TableException(
+ "Time-based join conditions must reference the time
attribute of both input tables.")
+ }
+ case other =>
+ val timeIndicators = extractTimeIndicatorAccesses(other,
leftFieldCount, inputType)
+ timeIndicators match {
+ case Seq() =>
+ (Seq(), Seq(other))
+ case _ =>
+ throw new TableException("Time indicators can not be used in
non time-condition.")
+ }
+ }
+ }
+
+ /**
+ * Extracts all time indicator attributes that are accessed in an
expression.
+ *
+ * @return seq(timeType, is left input time indicator)
+ */
+ def extractTimeIndicatorAccesses(
+ expression: RexNode,
+ leftFieldCount: Int,
+ inputType: RelDataType): Seq[(RelDataType, Boolean)] = {
+
+ expression match {
+ case i: RexInputRef =>
+ val idx = i.getIndex
+ inputType.getFieldList.get(idx).getType match {
+ case t: TimeIndicatorRelDataType if idx < leftFieldCount =>
+ // left table time indicator
+ Seq((t, true))
+ case t: TimeIndicatorRelDataType =>
+ // right table time indicator
+ Seq((t, false))
+ case _ => Seq()
+ }
+ case c: RexCall =>
+ c.operands.asScala
+ .map(extractTimeIndicatorAccesses(_, leftFieldCount, inputType))
+ .reduce(_ ++ _)
+ case _ => Seq()
+ }
+ }
+
+ /**
+ * Computes the absolute bound on the left operand of a comparison
expression and
+ * whether the bound is an upper or lower bound.
+ *
+ * @return window boundary, is left lower bound
+ */
+ def extractTimeOffsetFromCondition(
+ timeTerm: RexNode,
+ isLeftExprBelongLeftTable: Boolean,
+ rexBuilder: RexBuilder,
+ config: TableConfig): (Long, Boolean) = {
+
+ val timeCall: RexCall = timeTerm.asInstanceOf[RexCall]
+
+ val isLeftLowerBound: Boolean =
+ timeTerm.getKind match {
+ // e.g a.proctime > b.proctime - 5 sec, then it's the lower bound
of a and the value is -5
+ // e.g b.proctime > a.proctime - 5 sec, then it's not the lower
bound of a but upper bound
+ case kind@(SqlKind.GREATER_THAN | SqlKind.GREATER_THAN_OR_EQUAL) =>
+ isLeftExprBelongLeftTable
+ // e.g a.proctime < b.proctime + 5 sec, the the upper bound of a
is 5
+ case kind@(SqlKind.LESS_THAN | SqlKind.LESS_THAN_OR_EQUAL) =>
+ !isLeftExprBelongLeftTable
+ case _ =>
+ throw new TableException("Unsupported time-condition.")
+ }
+
+ val (leftLiteral, rightLiteral) =
+ reduceTimeExpression(
+ timeCall.operands.get(0),
+ timeCall.operands.get(1),
+ rexBuilder,
+ config)
+ val tmpTimeOffset: Long =
+ if (isLeftExprBelongLeftTable) rightLiteral - leftLiteral else
leftLiteral - rightLiteral
+
+ val boundary =
+ tmpTimeOffset.signum * (
+ if (timeTerm.getKind == SqlKind.LESS_THAN || timeTerm.getKind ==
SqlKind.GREATER_THAN) {
+ tmpTimeOffset.abs - 1
+ } else {
+ tmpTimeOffset.abs
+ })
+
+ (boundary, isLeftLowerBound)
+ }
+
+ /**
+ * Calculates the time boundary by replacing the time attribute by a
zero literal
+ * and reducing the expression.
+ * For example:
+ * b.proctime - interval '1' second - interval '2' second will be
translated to
+ * 0 - 1000 - 2000
+ */
+ private def reduceTimeExpression(
+ leftRexNode: RexNode,
+ rightRexNode: RexNode,
+ rexBuilder: RexBuilder,
+ config: TableConfig): (Long, Long) = {
+
+ /**
+ * replace the rowtime/proctime with zero literal.
+ */
+ def replaceTimeFieldWithLiteral(expr: RexNode): RexNode = {
+ expr match {
+ case c: RexCall =>
+ // replace in call operands
+ val newOps =
c.operands.asScala.map(replaceTimeFieldWithLiteral(_)).asJava
+ rexBuilder.makeCall(c.getType, c.getOperator, newOps)
+ case i: RexInputRef if
FlinkTypeFactory.isTimeIndicatorType(i.getType) =>
+ // replace with timestamp
+ rexBuilder.makeZeroLiteral(expr.getType)
+ case _: RexInputRef =>
+ throw new TableException("Time join condition may only reference
time indicator fields.")
+ case _ => expr
+ }
+ }
+
+ val literalLeftRex = replaceTimeFieldWithLiteral(leftRexNode)
+ val literalRightRex = replaceTimeFieldWithLiteral(rightRexNode)
+
+ val exprReducer = new ExpressionReducer(config)
+ val originList = new util.ArrayList[RexNode]()
+ originList.add(literalLeftRex)
+ originList.add(literalRightRex)
+ val reduceList = new util.ArrayList[RexNode]()
+ exprReducer.reduce(rexBuilder, originList, reduceList)
+
+ val literals = reduceList.asScala.map(f => f match {
--- End diff --
Can be simplified to
```scala
val literals = reduceList.asScala.map {
case literal: RexLiteral =>
literal.getValue2.asInstanceOf[Long]
case _ =>
throw TableException(
"Time condition may only consist of time attributes, literals,
and arithmetic operators.")
}
```
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