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/*
* 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.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import io.trino.matching.Capture;
import io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.matching.PropertyPattern;
import io.trino.sql.ir.Expression;
import io.trino.sql.planner.OrderingScheme;
import io.trino.sql.planner.Symbol;
import io.trino.sql.planner.SymbolsExtractor;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.Assignments;
import io.trino.sql.planner.plan.PlanNode;
import io.trino.sql.planner.plan.ProjectNode;
import io.trino.sql.planner.plan.WindowNode;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static io.trino.matching.Capture.newCapture;
import static io.trino.sql.planner.iterative.rule.Util.restrictOutputs;
import static io.trino.sql.planner.iterative.rule.Util.transpose;
import static io.trino.sql.planner.optimizations.WindowNodeUtil.dependsOn;
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;
public final class GatherAndMergeWindows
{
private GatherAndMergeWindows() {}
public static Set> rules()
{
// TODO convert to a pattern that allows for a sequence of ProjectNode, instead
// of a canned number, once the pattern system supports it.
return IntStream.range(0, 5)
.boxed()
.flatMap(numProjects ->
Stream.of(
new MergeAdjacentWindowsOverProjects(numProjects),
new SwapAdjacentWindowsBySpecifications(numProjects)))
.collect(toImmutableSet());
}
private abstract static class ManipulateAdjacentWindowsOverProjects
implements Rule
{
private final Capture childCapture = newCapture();
private final List> projectCaptures;
private final Pattern pattern;
protected ManipulateAdjacentWindowsOverProjects(int numProjects)
{
PropertyPattern childPattern = source().matching(window().capturedAs(childCapture));
ImmutableList.Builder> projectCapturesBuilder = ImmutableList.builder();
for (int i = 0; i < numProjects; ++i) {
Capture projectCapture = newCapture();
projectCapturesBuilder.add(projectCapture);
childPattern = source().matching(project().capturedAs(projectCapture).with(childPattern));
}
this.projectCaptures = projectCapturesBuilder.build();
this.pattern = window().with(childPattern);
}
@Override
public Pattern getPattern()
{
return pattern;
}
@Override
public Result apply(WindowNode parent, Captures captures, Context context)
{
// Pulling the descendant WindowNode above projects is done as a part of this rule, as opposed in a
// separate rule, because that pullup is not useful on its own, and could be undone by other rules.
// For example, a rule could insert a project-off node between adjacent WindowNodes that use different
// input symbols.
List projects = projectCaptures.stream()
.map(captures::get)
.collect(toImmutableList());
return pullWindowNodeAboveProjects(captures.get(childCapture), projects)
.flatMap(newChild -> manipulateAdjacentWindowNodes(parent, newChild, context))
.map(Result::ofPlanNode)
.orElse(Result.empty());
}
protected abstract Optional manipulateAdjacentWindowNodes(WindowNode parent, WindowNode child, Context context);
/**
* Looks for the pattern (ProjectNode*)WindowNode, and rewrites it to WindowNode(ProjectNode*),
* returning an empty option if it can't rewrite the projects, for example because they rely on
* the output of the WindowNode.
*
* @param projects the nodes above the target, bottom first.
*/
protected static Optional pullWindowNodeAboveProjects(
WindowNode target,
List projects)
{
if (projects.isEmpty()) {
return Optional.of(target);
}
PlanNode targetChild = target.getSource();
Set targetInputs = ImmutableSet.copyOf(targetChild.getOutputSymbols());
Set targetOutputs = ImmutableSet.copyOf(target.getOutputSymbols());
PlanNode newTargetChild = targetChild;
for (ProjectNode project : projects) {
Set newTargetChildOutputs = ImmutableSet.copyOf(newTargetChild.getOutputSymbols());
// The only kind of use of the output of the target that we can safely ignore is a simple identity propagation.
// The target node, when hoisted above the projections, will provide the symbols directly.
Map assignmentsWithoutTargetOutputIdentities = Maps.filterKeys(
project.getAssignments().getMap(),
output -> !(project.getAssignments().isIdentity(output) && targetOutputs.contains(output)));
if (targetInputs.stream().anyMatch(assignmentsWithoutTargetOutputIdentities::containsKey)) {
// Redefinition of an input to the target -- can't handle this case.
return Optional.empty();
}
Assignments newAssignments = Assignments.builder()
.putAll(assignmentsWithoutTargetOutputIdentities)
.putIdentities(targetInputs)
.build();
if (!newTargetChildOutputs.containsAll(SymbolsExtractor.extractUnique(newAssignments.getExpressions()))) {
// Projection uses an output of the target -- can't move the target above this projection.
return Optional.empty();
}
newTargetChild = new ProjectNode(project.getId(), newTargetChild, newAssignments);
}
WindowNode newTarget = (WindowNode) target.replaceChildren(ImmutableList.of(newTargetChild));
Set newTargetOutputs = ImmutableSet.copyOf(newTarget.getOutputSymbols());
if (!newTargetOutputs.containsAll(projects.getLast().getOutputSymbols())) {
// The new target node is hiding some of the projections, which makes this rewrite incorrect.
return Optional.empty();
}
return Optional.of(newTarget);
}
}
public static class MergeAdjacentWindowsOverProjects
extends ManipulateAdjacentWindowsOverProjects
{
public MergeAdjacentWindowsOverProjects(int numProjects)
{
super(numProjects);
}
@Override
protected Optional manipulateAdjacentWindowNodes(WindowNode parent, WindowNode child, Context context)
{
if (!child.getSpecification().equals(parent.getSpecification()) || dependsOn(parent, child)) {
return Optional.empty();
}
ImmutableMap.Builder functionsBuilder = ImmutableMap.builder();
functionsBuilder.putAll(parent.getWindowFunctions());
functionsBuilder.putAll(child.getWindowFunctions());
WindowNode mergedWindowNode = new WindowNode(
parent.getId(),
child.getSource(),
parent.getSpecification(),
functionsBuilder.buildOrThrow(),
parent.getHashSymbol(),
parent.getPrePartitionedInputs(),
parent.getPreSortedOrderPrefix());
return Optional.of(
restrictOutputs(context.getIdAllocator(), mergedWindowNode, ImmutableSet.copyOf(parent.getOutputSymbols()))
.orElse(mergedWindowNode));
}
}
public static class SwapAdjacentWindowsBySpecifications
extends ManipulateAdjacentWindowsOverProjects
{
public SwapAdjacentWindowsBySpecifications(int numProjects)
{
super(numProjects);
}
@Override
protected Optional manipulateAdjacentWindowNodes(WindowNode parent, WindowNode child, Context context)
{
if ((compare(parent, child) < 0) && !dependsOn(parent, child)) {
PlanNode transposedWindows = transpose(parent, child);
return Optional.of(
restrictOutputs(context.getIdAllocator(), transposedWindows, ImmutableSet.copyOf(parent.getOutputSymbols()))
.orElse(transposedWindows));
}
return Optional.empty();
}
private static int compare(WindowNode o1, WindowNode o2)
{
int comparison = comparePartitionBy(o1, o2);
if (comparison != 0) {
return comparison;
}
comparison = compareOrderBy(o1, o2);
if (comparison != 0) {
return comparison;
}
// If PartitionBy and OrderBy clauses are identical, let's establish an arbitrary order to prevent non-deterministic results of swapping WindowNodes in such a case
return o1.getId().toString().compareTo(o2.getId().toString());
}
private static int comparePartitionBy(WindowNode o1, WindowNode o2)
{
Iterator iterator1 = o1.getPartitionBy().iterator();
Iterator iterator2 = o2.getPartitionBy().iterator();
while (iterator1.hasNext() && iterator2.hasNext()) {
Symbol symbol1 = iterator1.next();
Symbol symbol2 = iterator2.next();
int partitionByComparison = symbol1.name().compareTo(symbol2.name());
if (partitionByComparison != 0) {
return partitionByComparison;
}
}
if (iterator1.hasNext()) {
return 1;
}
if (iterator2.hasNext()) {
return -1;
}
return 0;
}
private static int compareOrderBy(WindowNode o1, WindowNode o2)
{
if (o1.getOrderingScheme().isEmpty() && o2.getOrderingScheme().isEmpty()) {
return 0;
}
if (o1.getOrderingScheme().isPresent() && o2.getOrderingScheme().isEmpty()) {
return 1;
}
if (o1.getOrderingScheme().isEmpty() && o2.getOrderingScheme().isPresent()) {
return -1;
}
OrderingScheme o1OrderingScheme = o1.getOrderingScheme().get();
OrderingScheme o2OrderingScheme = o2.getOrderingScheme().get();
Iterator iterator1 = o1OrderingScheme.orderBy().iterator();
Iterator iterator2 = o2OrderingScheme.orderBy().iterator();
while (iterator1.hasNext() && iterator2.hasNext()) {
Symbol symbol1 = iterator1.next();
Symbol symbol2 = iterator2.next();
int orderByComparison = symbol1.name().compareTo(symbol2.name());
if (orderByComparison != 0) {
return orderByComparison;
}
int sortOrderComparison = o1OrderingScheme.ordering(symbol1).compareTo(o2OrderingScheme.ordering(symbol2));
if (sortOrderComparison != 0) {
return sortOrderComparison;
}
}
if (iterator1.hasNext()) {
return 1;
}
if (iterator2.hasNext()) {
return -1;
}
return 0;
}
}
}
