kasakrisz commented on code in PR #3588: URL: https://github.com/apache/hive/pull/3588#discussion_r977557467
########## ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveRemoveEmptySingleRules.java: ########## @@ -0,0 +1,291 @@ +/* + * 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.hadoop.hive.ql.optimizer.calcite.rules; + +import org.apache.calcite.plan.RelOptRule; +import org.apache.calcite.plan.RelOptRuleCall; +import org.apache.calcite.plan.RelOptUtil; +import org.apache.calcite.plan.RelRule; +import org.apache.calcite.plan.hep.HepRelVertex; +import org.apache.calcite.plan.volcano.RelSubset; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.Aggregate; +import org.apache.calcite.rel.core.Filter; +import org.apache.calcite.rel.core.Join; +import org.apache.calcite.rel.core.JoinRelType; +import org.apache.calcite.rel.core.Project; +import org.apache.calcite.rel.core.Sort; +import org.apache.calcite.rel.core.Union; +import org.apache.calcite.rel.core.Values; +import org.apache.calcite.rel.rules.PruneEmptyRules; +import org.apache.calcite.rel.type.RelDataType; +import org.apache.calcite.rel.type.RelDataTypeField; +import org.apache.calcite.rex.RexBuilder; +import org.apache.calcite.rex.RexInputRef; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.tools.RelBuilder; +import org.apache.hadoop.hive.ql.optimizer.calcite.HiveRelFactories; +import org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveValues; + +import java.util.ArrayList; +import java.util.List; + +/** + * This class provides access to Calcite's {@link PruneEmptyRules}. + * The instances of the rules use {@link org.apache.hadoop.hive.ql.optimizer.calcite.HiveRelBuilder}. + */ +public class HiveRemoveEmptySingleRules extends PruneEmptyRules { + + public static final RelOptRule PROJECT_INSTANCE = + RelRule.Config.EMPTY + .withDescription("HivePruneEmptyProject") + .as(PruneEmptyRules.RemoveEmptySingleRule.Config.class) + .withOperandFor(Project.class, project -> true) + .withRelBuilderFactory(HiveRelFactories.HIVE_BUILDER) + .toRule(); + + public static final RelOptRule FILTER_INSTANCE = + RelRule.Config.EMPTY + .withDescription("HivePruneEmptyFilter") + .as(PruneEmptyRules.RemoveEmptySingleRule.Config.class) + .withOperandFor(Filter.class, singleRel -> true) + .withRelBuilderFactory(HiveRelFactories.HIVE_BUILDER) + .toRule(); + + public static final RelOptRule JOIN_LEFT_INSTANCE = + RelRule.Config.EMPTY + .withOperandSupplier(b0 -> + b0.operand(Join.class).inputs( + b1 -> b1.operand(Values.class) + .predicate(Values::isEmpty).noInputs(), + b2 -> b2.operand(RelNode.class).anyInputs())) + .withDescription("HivePruneEmptyJoin(left)") + .as(JoinLeftEmptyRuleConfig.class) + .withRelBuilderFactory(HiveRelFactories.HIVE_BUILDER) + .toRule(); + + /** + * Improved version of Calcite's {@link PruneEmptyRules.JoinLeftEmptyRuleConfig}. + * In case of right outer join if the left branch is empty the join operator can be removed + * and take the right branch only. + * + * select * from (select * from emp where 1=0) right join dept + * to + * select null as emp.col0 ... null as emp.coln, dept.* from dept + */ + public interface JoinLeftEmptyRuleConfig extends PruneEmptyRule.Config { + @Override default PruneEmptyRule toRule() { + return new PruneEmptyRule(this) { + @Override public void onMatch(RelOptRuleCall call) { + Join join = call.rel(0); + HiveValues empty = call.rel(1); + RelNode right = call.rel(2); + RexBuilder rexBuilder = call.builder().getRexBuilder(); + if (join.getJoinType().generatesNullsOnLeft()) { + // "select * from emp right join dept" is not necessarily empty if + // emp is empty + List<RexNode> projects = new ArrayList<>( + empty.getRowType().getFieldCount() + right.getRowType().getFieldCount()); + List<String> columnNames = new ArrayList<>( + empty.getRowType().getFieldCount() + right.getRowType().getFieldCount()); + // left + addNullLiterals(rexBuilder, empty, projects, columnNames); + // right + copyProjects(rexBuilder, right.getRowType(), + join.getRowType(), empty.getRowType().getFieldCount(), projects, columnNames); + + RelNode project = call.builder().push(right).project(projects, columnNames).build(); + call.transformTo(project); + return; + } + call.transformTo(call.builder().push(join).empty().build()); + } + }; + } + } + + private static void addNullLiterals( + RexBuilder rexBuilder, HiveValues empty, List<RexNode> projectFields, List<String> newColumnNames) { + for (int i = 0; i < empty.getRowType().getFieldList().size(); ++i) { + RelDataTypeField relDataTypeField = empty.getRowType().getFieldList().get(i); + RexNode nullLiteral = rexBuilder.makeNullLiteral(relDataTypeField.getType()); + projectFields.add(nullLiteral); + newColumnNames.add(empty.getRowType().getFieldList().get(i).getName()); + } + } + + public static void copyProjects(RexBuilder rexBuilder, RelDataType inRowType, + RelDataType castRowType, int castRowTypeOffset, + List<RexNode> outProjects, List<String> outProjectNames) { + + for (int i = 0; i < inRowType.getFieldCount(); ++i) { + RelDataTypeField relDataTypeField = inRowType.getFieldList().get(i); + RexInputRef inputRef = rexBuilder.makeInputRef(relDataTypeField.getType(), i); + RexNode cast = rexBuilder.makeCast( + castRowType.getFieldList().get(castRowTypeOffset + i).getType(), inputRef); Review Comment: Moved to after the ruleconfigs hadle joins. -- This is an automated message from the Apache Git Service. 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