Github user KurtYoung commented on a diff in the pull request:
https://github.com/apache/flink/pull/3594#discussion_r111857715
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/rel/logical/FlinkLogicalJoin.scala
---
@@ -0,0 +1,130 @@
+/*
+ * 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.rel.logical
+
+import org.apache.calcite.plan._
+import org.apache.calcite.plan.volcano.RelSubset
+import org.apache.calcite.rel.RelNode
+import org.apache.calcite.rel.convert.ConverterRule
+import org.apache.calcite.rel.core._
+import org.apache.calcite.rel.logical.LogicalJoin
+import org.apache.calcite.rel.metadata.RelMetadataQuery
+import org.apache.calcite.rex.RexNode
+import org.apache.flink.table.rel.FlinkConventions
+
+import scala.collection.JavaConverters._
+
+class FlinkLogicalJoin(
+ cluster: RelOptCluster,
+ traitSet: RelTraitSet,
+ left: RelNode,
+ right: RelNode,
+ condition: RexNode,
+ joinType: JoinRelType)
+ extends Join(cluster, traitSet, left, right, condition,
Set.empty[CorrelationId].asJava, joinType)
+ with FlinkLogicalRel {
+
+ override def copy(
+ traitSet: RelTraitSet,
+ conditionExpr: RexNode,
+ left: RelNode,
+ right: RelNode,
+ joinType: JoinRelType,
+ semiJoinDone: Boolean): Join = {
+
+ new FlinkLogicalJoin(cluster, traitSet, left, right, conditionExpr,
joinType)
+ }
+
+ override def computeSelfCost (planner: RelOptPlanner, metadata:
RelMetadataQuery): RelOptCost = {
+ val leftRowCnt = metadata.getRowCount(getLeft)
+ val leftRowSize = estimateRowSize(getLeft.getRowType)
+
+ val rightRowCnt = metadata.getRowCount(getRight)
+ val rightRowSize = estimateRowSize(getRight.getRowType)
+
+ val ioCost = (leftRowCnt * leftRowSize) + (rightRowCnt * rightRowSize)
+ val cpuCost = leftRowCnt + rightRowCnt
+ val rowCnt = leftRowCnt + rightRowCnt
+
+ planner.getCostFactory.makeCost(rowCnt, cpuCost, ioCost)
+ }
+}
+
+private class FlinkLogicalJoinConverter
+ extends ConverterRule(
+ classOf[LogicalJoin],
+ Convention.NONE,
+ FlinkConventions.LOGICAL,
+ "FlinkLogicalJoinConverter") {
+
+ override def matches(call: RelOptRuleCall): Boolean = {
+ val join: LogicalJoin = call.rel(0).asInstanceOf[LogicalJoin]
+ val joinInfo = join.analyzeCondition
+
+ hasEqualityPredicates(join, joinInfo) || isSingleRowInnerJoin(join)
--- End diff --
Currently the answer is yes, because the physical join can only support
equation condition with simple keys.
If the join key is express like `a + 1 = b - 2`, if we don't have this
restriction in logical layer, the join condition will be like this and we can't
translate to physical join. There are 2 possible solutions:
1. keep it this way
2. Re-introduce rules which can exact expression out of join condition and
add addition "Calc" node to keep join key as simple field.
I prefer 1 for now, and keep 2 in mind. After all, it's not very nice to
let logical layer know all these restrictions. What do you think?
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