mihaibudiu commented on code in PR #3883: URL: https://github.com/apache/calcite/pull/3883#discussion_r1708517177
########## core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableAsofJoin.java: ########## @@ -0,0 +1,253 @@ +/* + * 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.calcite.adapter.enumerable; + +import org.apache.calcite.linq4j.tree.BlockBuilder; +import org.apache.calcite.linq4j.tree.Expression; +import org.apache.calcite.linq4j.tree.Expressions; +import org.apache.calcite.plan.DeriveMode; +import org.apache.calcite.plan.RelOptCluster; +import org.apache.calcite.plan.RelOptCost; +import org.apache.calcite.plan.RelOptPlanner; +import org.apache.calcite.plan.RelTraitSet; +import org.apache.calcite.rel.RelCollation; +import org.apache.calcite.rel.RelCollationTraitDef; +import org.apache.calcite.rel.RelCollations; +import org.apache.calcite.rel.RelFieldCollation; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.CorrelationId; +import org.apache.calcite.rel.core.Join; +import org.apache.calcite.rel.core.JoinRelType; +import org.apache.calcite.rel.logical.LogicalAsofJoin; +import org.apache.calcite.rel.metadata.RelMdCollation; +import org.apache.calcite.rel.metadata.RelMetadataQuery; +import org.apache.calcite.rex.RexCall; +import org.apache.calcite.rex.RexInputRef; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.sql.SqlKind; +import org.apache.calcite.util.BuiltInMethod; +import org.apache.calcite.util.Pair; + +import com.google.common.collect.ImmutableList; + +import org.checkerframework.checker.nullness.qual.Nullable; + +import java.util.ArrayList; +import java.util.List; +import java.util.Set; + +/** Implementation of {@link LogicalAsofJoin} in + * {@link EnumerableConvention enumerable calling convention}. */ +public class EnumerableAsofJoin extends Join implements EnumerableRel { + // This implementation is based on {@link EnumerableHashJoin} + + /** Compared to standard joins, ASOF joins have an additional condition for comparing timestamps. + * This is the additional condition. */ + final RexNode matchCondition; + + /** Creates an EnumerableAsofJoin. + * + * <p>Use {@link #create} unless you know what you're doing. */ + protected EnumerableAsofJoin( + RelOptCluster cluster, + RelTraitSet traits, + RelNode left, + RelNode right, + RexNode condition, + RexNode matchCondition, + Set<CorrelationId> variablesSet, + JoinRelType joinType) { + super( + cluster, + traits, + ImmutableList.of(), + left, + right, + condition, + variablesSet, + joinType); + this.matchCondition = matchCondition; + } + + /** Creates an EnumerableAsofJoin. */ + public static EnumerableAsofJoin create( + RelNode left, + RelNode right, + RexNode condition, + RexNode matchCondition, + Set<CorrelationId> variablesSet, + JoinRelType joinType) { + final RelOptCluster cluster = left.getCluster(); + final RelMetadataQuery mq = cluster.getMetadataQuery(); + final RelTraitSet traitSet = + cluster.traitSetOf(EnumerableConvention.INSTANCE) + .replaceIfs(RelCollationTraitDef.INSTANCE, + () -> RelMdCollation.enumerableHashJoin(mq, left, right, joinType)); + return new EnumerableAsofJoin(cluster, traitSet, left, right, condition, matchCondition, + variablesSet, joinType); + } + + @Override public EnumerableAsofJoin copy(RelTraitSet traitSet, RexNode condition, + RelNode left, RelNode right, JoinRelType joinType, + boolean semiJoinDone) { + // This method does not know about the matchCondition, so it should not be called + throw new RuntimeException("This method should not be called"); + } + + @Override public Join copy(RelTraitSet traitSet, List<RelNode> inputs) { + assert inputs.size() == 2; + return new EnumerableAsofJoin( + getCluster(), traitSet, inputs.get(0), inputs.get(1), + getCondition(), matchCondition, variablesSet, joinType); + } + + @Override public @Nullable Pair<RelTraitSet, List<RelTraitSet>> passThroughTraits( + final RelTraitSet required) { + return EnumerableTraitsUtils.passThroughTraitsForJoin( + required, joinType, left.getRowType().getFieldCount(), getTraitSet()); + } + + @Override public @Nullable Pair<RelTraitSet, List<RelTraitSet>> deriveTraits( + final RelTraitSet childTraits, final int childId) { + // should only derive traits (limited to collation for now) from left join input. + return EnumerableTraitsUtils.deriveTraitsForJoin( + childTraits, childId, joinType, getTraitSet(), right.getTraitSet()); + } + + @Override public DeriveMode getDeriveMode() { + return DeriveMode.LEFT_FIRST; + } + + @Override public @Nullable RelOptCost computeSelfCost(RelOptPlanner planner, + RelMetadataQuery mq) { + double rowCount = mq.getRowCount(this); + return planner.getCostFactory().makeCost(rowCount, 0, 0); + } + + /** Generate the function that compares two rows from the right collection on their + * timestamp field. + * + * @param rightCollectionType Type of data in right collection. + * @param kind Comparison kind. + * @param timestampFieldIndex Index of the field that is the timestamp field. + */ + private Expression generateTimestampComparator( + PhysType rightCollectionType, SqlKind kind, int timestampFieldIndex) { + RelFieldCollation.Direction direction; + switch (kind) { + case LESS_THAN: + case LESS_THAN_OR_EQUAL: + direction = RelFieldCollation.Direction.ASCENDING; + break; + case GREATER_THAN: + case GREATER_THAN_OR_EQUAL: + direction = RelFieldCollation.Direction.DESCENDING; + break; + default: + throw new RuntimeException("Unexpected timestamp comparison in ASOF join " + kind); + } + + final List<RelFieldCollation> fieldCollations = new ArrayList<>(1); + fieldCollations.add( + new RelFieldCollation(timestampFieldIndex, direction, + RelFieldCollation.NullDirection.FIRST)); + final RelCollation collation = RelCollations.of(fieldCollations); + return rightCollectionType.generateComparator(collation); + } + + /** Extract from a comparison 'call' the index of the field from + * the inner collection that is used in the comparison. */ + private int getTimestampFieldIndex(RexCall call) { + int timestampFieldIndex; + int leftFieldCount = left.getRowType().getFieldCount(); + List<RexNode> operands = call.getOperands(); + assert operands.size() == 2; + RexNode compareLeft = operands.get(0); + RexNode compareRight = operands.get(1); + assert compareLeft instanceof RexInputRef; + assert compareRight instanceof RexInputRef; + RexInputRef leftInputRef = (RexInputRef) compareLeft; + RexInputRef rightInputRef = (RexInputRef) compareRight; + // We know for sure that these two come from the inner and outer collection respectively, + // but we don't know which is which + if (leftInputRef.getIndex() < leftFieldCount) { + // Left input comes from the left collection + timestampFieldIndex = rightInputRef.getIndex() - leftFieldCount; + } else { + // Left input comes from the right collection + timestampFieldIndex = leftInputRef.getIndex() - leftFieldCount; + } + return timestampFieldIndex; + } + + @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) { + BlockBuilder builder = new BlockBuilder(); + final Result leftResult = + implementor.visitChild(this, 0, (EnumerableRel) left, pref); + Expression leftExpression = + builder.append( + "left", leftResult.block); + final Result rightResult = + implementor.visitChild(this, 1, (EnumerableRel) right, pref); + Expression rightExpression = + builder.append( + "right", rightResult.block); + final PhysType physType = + PhysTypeImpl.of( + implementor.getTypeFactory(), getRowType(), pref.preferArray()); + // ASOF joins conditions are restricted to equalities + assert joinInfo.nonEquiConditions.isEmpty(); + + // From the match condition we need to find out the kind of comparison performed + // and the timestamp field in the right collection. + assert matchCondition instanceof RexCall; + RexCall call = (RexCall) matchCondition; + SqlKind kind = call.getKind(); + int timestampFieldIndex = getTimestampFieldIndex(call); + + Expression timestampComparator = + generateTimestampComparator(rightResult.physType, kind, timestampFieldIndex); + + Expression matchPredicate = + EnumUtils.generatePredicate(implementor, getCluster().getRexBuilder(), + left, right, leftResult.physType, rightResult.physType, matchCondition); + return implementor.result( + physType, + builder.append( + Expressions.call( + leftExpression, + BuiltInMethod.ASOF_JOIN.method, + Expressions.list( + rightExpression, + // outer key selector + leftResult.physType.generateAccessorWithoutNulls(joinInfo.leftKeys), + // inner key selector + rightResult.physType.generateAccessorWithoutNulls(joinInfo.rightKeys), + // result selector + EnumUtils.joinSelector(joinType, + physType, + ImmutableList.of( + leftResult.physType, rightResult.physType))) + // match comparator + .append(matchPredicate) + // timestamp comparator + .append(timestampComparator) Review Comment: "timestamp" is just a name for a pair of columns from each side that are being compared. It has nothing to do with the TIMESTAMP data type. The MATCH_CONDITION is restricted to one comparison between a pair of columns from either side. That's enforced by the validator, and part of the spec. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
