[GitHub] [flink] godfreyhe commented on a change in pull request #8440: [FLINK-12509] [table-planner-blink] Introduce planner rules about non semi/anti join

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godfreyhe commented on a change in pull request #8440: [FLINK-12509] [table-planner-blink] Introduce planner rules about non semi/anti join
URL: https://github.com/apache/flink/pull/8440#discussion_r286013468
 
 

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 File path: flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/plan/rules/logical/JoinConditionTypeCoerceRule.scala
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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.flink.table.plan.rules.logical
+
+import org.apache.flink.table.api.TableException
+import org.apache.flink.table.plan.util.FlinkRexUtil
+
+import org.apache.calcite.plan.RelOptRule.{any, operand}
+import org.apache.calcite.plan.{RelOptRule, RelOptRuleCall, RelOptUtil}
+import org.apache.calcite.rel.`type`.RelDataTypeFactory
+import org.apache.calcite.rel.core.Join
+import org.apache.calcite.rex.{RexCall, RexInputRef, RexNode}
+import org.apache.calcite.sql.SqlKind
+import org.apache.calcite.sql.`type`.SqlTypeUtil
+
+import scala.collection.JavaConversions._
+import scala.collection.mutable
+
+/**
+  * Planner rule that coerces the both sides of EQUALS(`=`) operator in Join condition
+  * to the same type while sans nullability.
+  *
+  * <p>For most cases, we already did the type coercion during type validation by implicit
+  * type coercion or during sqlNode to relNode conversion, this rule just does a rechecking
+  * to ensure a strongly uniform equals type, so that during a HashJoin shuffle we can have
+  * the same hashcode of the same value.
+  */
+class JoinConditionTypeCoerceRule extends RelOptRule(
 
 Review comment:
   for non SEMI/ANTI join, type coerce is done in Calcite;  and for the SEMI/ANTI join, type coerce is done in this rule because Calcite does not check SubQuery.

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