Rewrite AGG(IF()) to AGG() FILTER() #16534
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,197 @@ | ||
| /* | ||
| * Licensed 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 com.facebook.presto.sql.planner.iterative.rule; | ||
|
|
||
| import com.facebook.presto.Session; | ||
| import com.facebook.presto.matching.Capture; | ||
| import com.facebook.presto.matching.Captures; | ||
| import com.facebook.presto.matching.Pattern; | ||
| import com.facebook.presto.spi.plan.AggregationNode; | ||
| import com.facebook.presto.spi.plan.AggregationNode.Aggregation; | ||
| import com.facebook.presto.spi.plan.Assignments; | ||
| import com.facebook.presto.spi.plan.FilterNode; | ||
| import com.facebook.presto.spi.plan.ProjectNode; | ||
| import com.facebook.presto.spi.relation.CallExpression; | ||
| import com.facebook.presto.spi.relation.RowExpression; | ||
| import com.facebook.presto.spi.relation.SpecialFormExpression; | ||
| import com.facebook.presto.spi.relation.VariableReferenceExpression; | ||
| import com.facebook.presto.sql.planner.iterative.Rule; | ||
| import com.facebook.presto.sql.relational.Expressions; | ||
| import com.google.common.collect.ImmutableList; | ||
| import com.google.common.collect.ImmutableMap; | ||
| import com.google.common.collect.ImmutableSortedSet; | ||
|
|
||
| import java.util.HashMap; | ||
| import java.util.Map; | ||
| import java.util.Optional; | ||
| import java.util.Set; | ||
|
|
||
| import static com.facebook.presto.SystemSessionProperties.isAggregationIfToFilterRewriteEnabled; | ||
| import static com.facebook.presto.expressions.LogicalRowExpressions.TRUE_CONSTANT; | ||
| import static com.facebook.presto.expressions.LogicalRowExpressions.or; | ||
| import static com.facebook.presto.matching.Capture.newCapture; | ||
| import static com.facebook.presto.spi.relation.SpecialFormExpression.Form.IF; | ||
| import static com.facebook.presto.sql.planner.plan.Patterns.aggregation; | ||
| import static com.facebook.presto.sql.planner.plan.Patterns.project; | ||
| import static com.facebook.presto.sql.planner.plan.Patterns.source; | ||
| import static com.google.common.collect.ImmutableSet.toImmutableSet; | ||
| import static com.google.common.collect.ImmutableSortedMap.toImmutableSortedMap; | ||
| import static java.util.function.Function.identity; | ||
|
|
||
| /** | ||
| * A optimizer rule which rewrites | ||
| * AGG(IF(condition, expr)) | ||
| * to | ||
| * AGG(expr) FILTER (WHERE condition). | ||
| * <p> | ||
| * The latter plan is more efficient because: | ||
| * 1. The filter can be pushed down to the scan node. | ||
| * 2. The rows not matching the condition are not aggregated. | ||
| * 3. The IF() expression wrapper is removed. | ||
| */ | ||
| public class RewriteAggregationIfToFilter | ||
| implements Rule<AggregationNode> | ||
| { | ||
| private static final Capture<ProjectNode> CHILD = newCapture(); | ||
|
|
||
| private static final Pattern<AggregationNode> PATTERN = aggregation() | ||
| .with(source().matching(project().capturedAs(CHILD))); | ||
|
|
||
| @Override | ||
| public boolean isEnabled(Session session) | ||
| { | ||
| return isAggregationIfToFilterRewriteEnabled(session); | ||
| } | ||
|
|
||
| @Override | ||
| public Pattern<AggregationNode> getPattern() | ||
| { | ||
| return PATTERN; | ||
| } | ||
|
|
||
| @Override | ||
| public Result apply(AggregationNode aggregationNode, Captures captures, Context context) | ||
| { | ||
| ProjectNode sourceProject = captures.get(CHILD); | ||
|
|
||
| Set<Aggregation> aggregationsToRewrite = aggregationNode.getAggregations().values().stream() | ||
| .filter(aggregation -> shouldRewriteAggregation(aggregation, sourceProject)) | ||
| .collect(toImmutableSet()); | ||
| if (aggregationsToRewrite.isEmpty()) { | ||
| return Result.empty(); | ||
| } | ||
|
|
||
| // Get the corresponding assignments in the input project. | ||
| // The aggregationReferences only has the aggregations to rewrite, thus the sourceAssignments only has IF expressions with NULL false results. | ||
| // Multiple aggregations may reference the same input. We use a map to dedup them based on the VariableReferenceExpression, so that we only do the rewrite once per input | ||
| // IF expression. | ||
| // The order of sourceAssignments determines the order of generating the new variables for the IF conditions and results. We use a sorted map to get a deterministic | ||
| // order based on the name of the VariableReferenceExpressions. | ||
| Map<VariableReferenceExpression, RowExpression> sourceAssignments = aggregationsToRewrite.stream() | ||
| .map(aggregation -> (VariableReferenceExpression) aggregation.getArguments().get(0)) | ||
| .collect(toImmutableSortedMap(VariableReferenceExpression::compareTo, identity(), variable -> sourceProject.getAssignments().get(variable), (left, right) -> left)); | ||
|
|
||
| Assignments.Builder newAssignments = Assignments.builder(); | ||
| // We don't remove the IF expression now in case the aggregation has other references to it. These will be cleaned up by the PruneUnreferencedOutputs rule later. | ||
| newAssignments.putAll(sourceProject.getAssignments()); | ||
|
|
||
| // Map from the aggregation reference to the IF condition reference. | ||
| Map<VariableReferenceExpression, VariableReferenceExpression> aggregationReferenceToConditionReference = new HashMap<>(); | ||
| // Map from the aggregation reference to the IF result reference. | ||
| Map<VariableReferenceExpression, VariableReferenceExpression> aggregationReferenceToIfResultReference = new HashMap<>(); | ||
|
|
||
| for (Map.Entry<VariableReferenceExpression, RowExpression> entry : sourceAssignments.entrySet()) { | ||
| VariableReferenceExpression outputVariable = entry.getKey(); | ||
| SpecialFormExpression ifExpression = (SpecialFormExpression) entry.getValue(); | ||
|
|
||
| RowExpression condition = ifExpression.getArguments().get(0); | ||
| VariableReferenceExpression conditionReference = context.getVariableAllocator().newVariable(condition); | ||
| newAssignments.put(conditionReference, condition); | ||
| aggregationReferenceToConditionReference.put(outputVariable, conditionReference); | ||
|
|
||
| RowExpression trueResult = ifExpression.getArguments().get(1); | ||
| VariableReferenceExpression ifResultReference = context.getVariableAllocator().newVariable(trueResult); | ||
| newAssignments.put(ifResultReference, trueResult); | ||
| aggregationReferenceToIfResultReference.put(outputVariable, ifResultReference); | ||
| } | ||
|
|
||
| // Build new aggregations. | ||
| ImmutableMap.Builder<VariableReferenceExpression, Aggregation> aggregations = ImmutableMap.builder(); | ||
| // Stores the masks used to build the filter predicates. Use set to dedup the predicates. | ||
| ImmutableSortedSet.Builder<VariableReferenceExpression> masks = ImmutableSortedSet.naturalOrder(); | ||
| for (Map.Entry<VariableReferenceExpression, Aggregation> entry : aggregationNode.getAggregations().entrySet()) { | ||
| VariableReferenceExpression output = entry.getKey(); | ||
| Aggregation aggregation = entry.getValue(); | ||
| if (!aggregationsToRewrite.contains(aggregation)) { | ||
| aggregations.put(output, aggregation); | ||
| continue; | ||
| } | ||
| VariableReferenceExpression aggregationReference = (VariableReferenceExpression) aggregation.getArguments().get(0); | ||
| CallExpression callExpression = aggregation.getCall(); | ||
| VariableReferenceExpression mask = aggregationReferenceToConditionReference.get(aggregationReference); | ||
| aggregations.put(output, new Aggregation( | ||
| new CallExpression( | ||
| callExpression.getDisplayName(), | ||
| callExpression.getFunctionHandle(), | ||
| callExpression.getType(), | ||
| ImmutableList.of(aggregationReferenceToIfResultReference.get(aggregationReference))), | ||
| Optional.empty(), | ||
| aggregation.getOrderBy(), | ||
| aggregation.isDistinct(), | ||
| Optional.of(aggregationReferenceToConditionReference.get(aggregationReference)))); | ||
| masks.add(mask); | ||
| } | ||
|
|
||
| RowExpression predicate = TRUE_CONSTANT; | ||
| if (!aggregationNode.hasNonEmptyGroupingSet() && aggregationsToRewrite.size() == aggregationNode.getAggregations().size()) { | ||
| // All aggregations are rewritten by this rule. We can add a filter with all the masks to make the query more efficient. | ||
| predicate = or(masks.build()); | ||
|
Contributor
There was a problem hiding this comment. This or might actually cause more slowdown than help because all masks have to be evaluated for every row anyway. I don't think this helps.
Contributor
Author
There was a problem hiding this comment. I think it helps because
Besides, the AGG() FILTER implementation also adds this predicate. It is better to keep the same behavior: |
||
| } | ||
| return Result.ofPlanNode( | ||
| new AggregationNode( | ||
| context.getIdAllocator().getNextId(), | ||
| new FilterNode( | ||
| context.getIdAllocator().getNextId(), | ||
| new ProjectNode( | ||
| context.getIdAllocator().getNextId(), | ||
| sourceProject.getSource(), | ||
| newAssignments.build()), | ||
| predicate), | ||
| aggregations.build(), | ||
| aggregationNode.getGroupingSets(), | ||
| aggregationNode.getPreGroupedVariables(), | ||
| aggregationNode.getStep(), | ||
| aggregationNode.getHashVariable(), | ||
| aggregationNode.getGroupIdVariable())); | ||
| } | ||
|
|
||
| private boolean shouldRewriteAggregation(Aggregation aggregation, ProjectNode sourceProject) | ||
| { | ||
| if (!(aggregation.getArguments().size() == 1 && aggregation.getArguments().get(0) instanceof VariableReferenceExpression)) { | ||
| // Currently we only handle aggregation with a single VariableReferenceExpression. The detailed expressions are in a project node below this aggregation. | ||
| return false; | ||
| } | ||
| if (aggregation.getFilter().isPresent() || aggregation.getMask().isPresent()) { | ||
| // Do not rewrite the aggregation if it already has a filter or mask. | ||
| return false; | ||
| } | ||
| RowExpression sourceExpression = sourceProject.getAssignments().get((VariableReferenceExpression) aggregation.getArguments().get(0)); | ||
| if (!(sourceExpression instanceof SpecialFormExpression)) { | ||
| return false; | ||
| } | ||
| SpecialFormExpression expression = (SpecialFormExpression) sourceExpression; | ||
| // Only rewrite the aggregation if the else branch is not present. | ||
| return expression.getForm() == IF && Expressions.isNull(expression.getArguments().get(2)); | ||
|
Contributor
There was a problem hiding this comment. You could also add when the else part is the null literal like IF(x, y, null) |
||
| } | ||
| } | ||
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Uh oh!
There was an error while loading. Please reload this page.