Remove redundant cast to varchar in join clause #21050
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| /* | ||
| * 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; | ||
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|
||
| import com.facebook.presto.Session; | ||
| import com.facebook.presto.common.type.Type; | ||
| import com.facebook.presto.common.type.VarcharType; | ||
| import com.facebook.presto.matching.Captures; | ||
| import com.facebook.presto.matching.Pattern; | ||
| import com.facebook.presto.metadata.FunctionAndTypeManager; | ||
| import com.facebook.presto.spi.plan.PlanNode; | ||
| 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.VariableReferenceExpression; | ||
| import com.facebook.presto.sql.planner.iterative.Rule; | ||
| import com.facebook.presto.sql.planner.plan.JoinNode; | ||
| import com.facebook.presto.sql.relational.FunctionResolution; | ||
| import com.google.common.collect.ImmutableList; | ||
| import com.google.common.collect.ImmutableMap; | ||
|
|
||
| import java.util.List; | ||
| import java.util.Map; | ||
| import java.util.Optional; | ||
|
|
||
| import static com.facebook.presto.SystemSessionProperties.isRemoveRedundantCastToVarcharInJoinEnabled; | ||
| import static com.facebook.presto.common.type.BigintType.BIGINT; | ||
| import static com.facebook.presto.common.type.IntegerType.INTEGER; | ||
| import static com.facebook.presto.sql.planner.PlannerUtils.addProjections; | ||
| import static com.facebook.presto.sql.planner.plan.Patterns.join; | ||
| import static com.facebook.presto.sql.relational.Expressions.castToBigInt; | ||
|
|
||
| /** | ||
| * Remove redundant cast to varchar in join condition for queries like `select select * from orders o join customer c on cast(o.custkey as varchar) = cast(c.custkey as varchar)` | ||
| * Transform from | ||
| * <pre> | ||
| * - Join | ||
| * left_cast = right_cast | ||
| * - Project | ||
| * left_cast := cast(lkey as varchar) | ||
| * - TableScan | ||
| * lkey BIGINT | ||
| * - Project | ||
| * right_cast := cast(rkey as varchar) | ||
| * - TableScan | ||
| * rkey BIGINT | ||
| * | ||
| * </pre> | ||
| * into | ||
| * <pre> | ||
| * - Join | ||
| * new_lkey = new_rkey | ||
| * - Project | ||
| * left_cast := cast(lkey as varchar) | ||
| * new_lkey := lkey | ||
| * - TableScan | ||
| * lkey BIGINT | ||
| * - Project | ||
| * right_cast := cast(rkey as varchar) | ||
| * new_rkey := rkey | ||
| * - TableScan | ||
| * rkey BIGINT | ||
| * </pre> | ||
| * We will rely on optimizations later to remove unnecessary cast (if not used) and identity projection here. | ||
| * <p> | ||
| * Notice that we do not apply similar optimizations to queries with similar join condition like `cast(bigint as varchar) = varchar`. In general it can be converted to | ||
|
||
| * `bigint = try_cast(varchar as bigint)` as if the varchar here cannot be converted to bigint, try_cast will return null and will not match anyway. However, a special case is | ||
| * varchar begins with 0. `select cast(92 as varchar) = '092'` is false, but `select 92 = try_cast('092' as bigint)` returns true. | ||
| */ | ||
| public class RemoveRedundantCastToVarcharInJoinClause | ||
| implements Rule<JoinNode> | ||
| { | ||
| private static final List<Type> TYPE_SUPPORTED = ImmutableList.of(INTEGER, BIGINT); | ||
| private final FunctionAndTypeManager functionAndTypeManager; | ||
| private final FunctionResolution functionResolution; | ||
|
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| public RemoveRedundantCastToVarcharInJoinClause(FunctionAndTypeManager functionAndTypeManager) | ||
| { | ||
| this.functionAndTypeManager = functionAndTypeManager; | ||
| this.functionResolution = new FunctionResolution(functionAndTypeManager.getFunctionAndTypeResolver()); | ||
| } | ||
|
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||
| @Override | ||
| public boolean isEnabled(Session session) | ||
| { | ||
| return isRemoveRedundantCastToVarcharInJoinEnabled(session); | ||
| } | ||
|
|
||
| @Override | ||
| public Pattern<JoinNode> getPattern() | ||
| { | ||
| return join(); | ||
| } | ||
|
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| @Override | ||
| public Result apply(JoinNode node, Captures captures, Context context) | ||
| { | ||
| PlanNode leftInput = context.getLookup().resolve(node.getLeft()); | ||
| PlanNode rightInput = context.getLookup().resolve(node.getRight()); | ||
| if (!(leftInput instanceof ProjectNode) || !(rightInput instanceof ProjectNode)) { | ||
|
||
| return Result.empty(); | ||
| } | ||
| ProjectNode leftProject = (ProjectNode) leftInput; | ||
| ProjectNode rightProject = (ProjectNode) rightInput; | ||
|
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| ImmutableList.Builder<JoinNode.EquiJoinClause> joinClauseBuilder = ImmutableList.builder(); | ||
| ImmutableMap.Builder<VariableReferenceExpression, RowExpression> newLeftAssignmentsBuilder = ImmutableMap.builder(); | ||
| ImmutableMap.Builder<VariableReferenceExpression, RowExpression> newRightAssignmentsBuilder = ImmutableMap.builder(); | ||
| boolean isChanged = false; | ||
| for (JoinNode.EquiJoinClause equiJoinClause : node.getCriteria()) { | ||
| RowExpression leftProjectAssignment = leftProject.getAssignments().getMap().get(equiJoinClause.getLeft()); | ||
| RowExpression rightProjectAssignment = rightProject.getAssignments().getMap().get(equiJoinClause.getRight()); | ||
| if (!isSupportedCast(leftProjectAssignment) || !isSupportedCast(rightProjectAssignment)) { | ||
| joinClauseBuilder.add(equiJoinClause); | ||
| continue; | ||
| } | ||
|
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| RowExpression leftAssignment = ((CallExpression) leftProjectAssignment).getArguments().get(0); | ||
| RowExpression rightAssignment = ((CallExpression) rightProjectAssignment).getArguments().get(0); | ||
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| if (!leftAssignment.getType().equals(rightAssignment.getType())) { | ||
| leftAssignment = castToBigInt(functionAndTypeManager, leftAssignment); | ||
|
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| rightAssignment = castToBigInt(functionAndTypeManager, rightAssignment); | ||
| } | ||
|
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| VariableReferenceExpression newLeft = context.getVariableAllocator().newVariable(leftAssignment); | ||
| newLeftAssignmentsBuilder.put(newLeft, leftAssignment); | ||
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| VariableReferenceExpression newRight = context.getVariableAllocator().newVariable(rightAssignment); | ||
| newRightAssignmentsBuilder.put(newRight, rightAssignment); | ||
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| joinClauseBuilder.add(new JoinNode.EquiJoinClause(newLeft, newRight)); | ||
| isChanged = true; | ||
| } | ||
|
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| if (!isChanged) { | ||
| return Result.empty(); | ||
| } | ||
|
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| newLeftAssignmentsBuilder.putAll(leftProject.getAssignments().getMap()); | ||
| Map<VariableReferenceExpression, RowExpression> newLeftAssignments = newLeftAssignmentsBuilder.build(); | ||
| newRightAssignmentsBuilder.putAll(rightProject.getAssignments().getMap()); | ||
| Map<VariableReferenceExpression, RowExpression> newRightAssignments = newRightAssignmentsBuilder.build(); | ||
|
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| PlanNode newLeftProject = addProjections(leftProject.getSource(), context.getIdAllocator(), newLeftAssignments); | ||
| PlanNode newRightProject = addProjections(rightProject.getSource(), context.getIdAllocator(), newRightAssignments); | ||
|
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| return Result.ofPlanNode(new JoinNode(node.getSourceLocation(), context.getIdAllocator().getNextId(), node.getType(), newLeftProject, newRightProject, joinClauseBuilder.build(), node.getOutputVariables(), node.getFilter(), Optional.empty(), Optional.empty(), node.getDistributionType(), node.getDynamicFilters())); | ||
| } | ||
|
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| private boolean isSupportedCast(RowExpression rowExpression) | ||
| { | ||
| if (rowExpression instanceof CallExpression && functionResolution.isCastFunction(((CallExpression) rowExpression).getFunctionHandle())) { | ||
| CallExpression cast = (CallExpression) rowExpression; | ||
| return TYPE_SUPPORTED.contains(cast.getArguments().get(0).getType()) && cast.getType() instanceof VarcharType; | ||
| } | ||
| return false; | ||
| } | ||
| } | ||
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why do we need a session property? isn't this always beneficial?
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Just in case we need to revert it if any bugs found later.