io.trino.sql.planner.iterative.rule.PushDownDereferencesThroughWindow Maven / Gradle / Ivy
/*
* 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 io.trino.sql.planner.iterative.rule;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.ImmutableList;
import io.trino.matching.Capture;
import io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.sql.planner.OrderingScheme;
import io.trino.sql.planner.Symbol;
import io.trino.sql.planner.TypeAnalyzer;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.Assignments;
import io.trino.sql.planner.plan.DataOrganizationSpecification;
import io.trino.sql.planner.plan.ProjectNode;
import io.trino.sql.planner.plan.WindowNode;
import io.trino.sql.tree.Expression;
import io.trino.sql.tree.SubscriptExpression;
import io.trino.sql.tree.SymbolReference;
import java.util.Map;
import java.util.Set;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.ImmutableMap.toImmutableMap;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static io.trino.matching.Capture.newCapture;
import static io.trino.sql.planner.ExpressionNodeInliner.replaceExpression;
import static io.trino.sql.planner.iterative.rule.DereferencePushdown.extractRowSubscripts;
import static io.trino.sql.planner.iterative.rule.DereferencePushdown.getBase;
import static io.trino.sql.planner.plan.Patterns.project;
import static io.trino.sql.planner.plan.Patterns.source;
import static io.trino.sql.planner.plan.Patterns.window;
import static java.util.Objects.requireNonNull;
/**
* Transforms:
*
* Project(G := f1(A.x), H := f2(B.x), J := f3(C.x), K := f4(D.x), L := f5(F))
* Window(orderBy = [B], partitionBy = [C], min_D := min(D))
* Source(A, B, C, D, E, F)
*
* to:
*
* Project(G := f1(symbol), H := f2(B.x), J := f3(C.x), K := f4(D.x), L := f5(F))
* Window(orderBy = [B], partitionBy = [C], min_D := min(D))
* Project(A, B, C, D, E, F, symbol := A.x)
* Source(A, B, C, D, E, F)
*
*
* Pushes down dereference projections through Window. Excludes dereferences on symbols in ordering scheme and partitionBy
* to avoid data replication, since these symbols cannot be pruned.
*/
public class PushDownDereferencesThroughWindow
implements Rule
{
private static final Capture CHILD = newCapture();
private final TypeAnalyzer typeAnalyzer;
public PushDownDereferencesThroughWindow(TypeAnalyzer typeAnalyzer)
{
this.typeAnalyzer = requireNonNull(typeAnalyzer, "typeAnalyzer is null");
}
@Override
public Pattern getPattern()
{
return project()
.with(source().matching(window().capturedAs(CHILD)));
}
@Override
public Result apply(ProjectNode projectNode, Captures captures, Context context)
{
WindowNode windowNode = captures.get(CHILD);
// Extract dereferences for pushdown
Set dereferences = extractRowSubscripts(
ImmutableList.builder()
.addAll(projectNode.getAssignments().getExpressions())
// also include dereference projections used in window functions
.addAll(windowNode.getWindowFunctions().values().stream()
.flatMap(function -> function.getArguments().stream())
.collect(toImmutableList()))
.build(),
false,
context.getSession(),
typeAnalyzer,
context.getSymbolAllocator().getTypes());
DataOrganizationSpecification specification = windowNode.getSpecification();
dereferences = dereferences.stream()
.filter(expression -> {
Symbol symbol = getBase(expression);
// Exclude partitionBy, orderBy and synthesized symbols
return !specification.getPartitionBy().contains(symbol) &&
!specification.getOrderingScheme().map(OrderingScheme::getOrderBy).orElse(ImmutableList.of()).contains(symbol) &&
!windowNode.getCreatedSymbols().contains(symbol);
})
.collect(toImmutableSet());
if (dereferences.isEmpty()) {
return Result.empty();
}
// Create new symbols for dereference expressions
Assignments dereferenceAssignments = Assignments.of(dereferences, context.getSession(), context.getSymbolAllocator(), typeAnalyzer);
// Rewrite project node assignments using new symbols for dereference expressions
Map mappings = HashBiMap.create(dereferenceAssignments.getMap())
.inverse()
.entrySet().stream()
.collect(toImmutableMap(Map.Entry::getKey, entry -> entry.getValue().toSymbolReference()));
Assignments newAssignments = projectNode.getAssignments().rewrite(expression -> replaceExpression(expression, mappings));
return Result.ofPlanNode(
new ProjectNode(
context.getIdAllocator().getNextId(),
new WindowNode(
windowNode.getId(),
new ProjectNode(
context.getIdAllocator().getNextId(),
windowNode.getSource(),
Assignments.builder()
.putIdentities(windowNode.getSource().getOutputSymbols())
.putAll(dereferenceAssignments)
.build()),
windowNode.getSpecification(),
// Replace dereference expressions in functions
windowNode.getWindowFunctions().entrySet().stream()
.collect(toImmutableMap(
Map.Entry::getKey,
entry -> {
WindowNode.Function oldFunction = entry.getValue();
return new WindowNode.Function(
oldFunction.getResolvedFunction(),
oldFunction.getArguments().stream()
.map(expression -> replaceExpression(expression, mappings))
.collect(toImmutableList()),
oldFunction.getFrame(),
oldFunction.isIgnoreNulls());
})),
windowNode.getHashSymbol(),
windowNode.getPrePartitionedInputs(),
windowNode.getPreSortedOrderPrefix()),
newAssignments));
}
}