/*
* 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.optimizations.joins;
import com.facebook.presto.sql.planner.Symbol;
import com.facebook.presto.sql.planner.plan.FilterNode;
import com.facebook.presto.sql.planner.plan.JoinNode;
import com.facebook.presto.sql.planner.plan.PlanNode;
import com.facebook.presto.sql.planner.plan.PlanNodeId;
import com.facebook.presto.sql.planner.plan.PlanVisitor;
import com.facebook.presto.sql.planner.plan.ProjectNode;
import com.facebook.presto.sql.tree.Expression;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Multimap;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import static com.facebook.presto.sql.planner.plan.JoinNode.Type.INNER;
import static com.google.common.base.Preconditions.checkState;
import static java.lang.String.format;
import static java.util.Objects.requireNonNull;
/**
* JoinGraph represents sequence of Joins, where nodes in the graph
* are PlanNodes that are being joined and edges are all equality join
* conditions between pair of nodes.
*/
public class JoinGraph
{
private final Optional<Map<Symbol, Expression>> assignments;
private final List<Expression> filters;
private final List<PlanNode> nodes; // nodes in order of their appearance in tree plan (left, right, parent)
private final Multimap<PlanNodeId, Edge> edges;
private final PlanNodeId rootId;
public static List<JoinGraph> buildFrom(PlanNode plan)
{
Context context = new Context();
JoinGraph graph = plan.accept(new Builder(), context);
if (graph.size() > 1) {
context.addSubGraph(graph);
}
return context.getGraphs();
}
public JoinGraph(PlanNode node)
{
this(ImmutableList.of(node), ImmutableMultimap.of(), node.getId(), ImmutableList.of(), Optional.empty());
}
public JoinGraph(
List<PlanNode> nodes,
Multimap<PlanNodeId, Edge> edges,
PlanNodeId rootId,
List<Expression> filters,
Optional<Map<Symbol, Expression>> assignments)
{
this.nodes = nodes;
this.edges = edges;
this.rootId = rootId;
this.filters = filters;
this.assignments = assignments;
}
public JoinGraph withAssignments(Map<Symbol, Expression> assignments)
{
return new JoinGraph(nodes, edges, rootId, filters, Optional.of(assignments));
}
public Optional<Map<Symbol, Expression>> getAssignments()
{
return assignments;
}
public JoinGraph withFilter(Expression expression)
{
ImmutableList.Builder<Expression> filters = ImmutableList.builder();
filters.addAll(this.filters);
filters.add(expression);
return new JoinGraph(nodes, edges, rootId, filters.build(), assignments);
}
public List<Expression> getFilters()
{
return filters;
}
public PlanNodeId getRootId()
{
return rootId;
}
public JoinGraph withRootId(PlanNodeId rootId)
{
return new JoinGraph(nodes, edges, rootId, filters, assignments);
}
public boolean isEmpty()
{
return nodes.isEmpty();
}
public int size()
{
return nodes.size();
}
public PlanNode getNode(int index)
{
return nodes.get(index);
}
public List<PlanNode> getNodes()
{
return nodes;
}
public Collection<Edge> getEdges(PlanNode node)
{
return ImmutableList.copyOf(edges.get(node.getId()));
}
@Override
public String toString()
{
StringBuilder builder = new StringBuilder();
for (PlanNode nodeFrom : nodes) {
builder.append(nodeFrom.getId())
.append(" = ")
.append(nodeFrom.toString())
.append("\n");
}
for (PlanNode nodeFrom : nodes) {
builder.append(nodeFrom.getId())
.append(":");
for (Edge nodeTo : edges.get(nodeFrom.getId())) {
builder.append(" ").append(nodeTo.getTargetNode().getId());
}
builder.append("\n");
}
return builder.toString();
}
private JoinGraph joinWith(JoinGraph other, List<JoinNode.EquiJoinClause> joinClauses, Context context, PlanNodeId newRoot)
{
for (PlanNode node : other.nodes) {
checkState(!edges.containsKey(node.getId()), format("Node [%s] appeared in two JoinGraphs", node));
}
List<PlanNode> nodes = ImmutableList.<PlanNode>builder()
.addAll(this.nodes)
.addAll(other.nodes)
.build();
ImmutableMultimap.Builder<PlanNodeId, Edge> edges = ImmutableMultimap.<PlanNodeId, Edge>builder()
.putAll(this.edges)
.putAll(other.edges);
List<Expression> joinedFilters = ImmutableList.<Expression>builder()
.addAll(this.filters)
.addAll(other.filters)
.build();
for (JoinNode.EquiJoinClause edge : joinClauses) {
Symbol leftSymbol = edge.getLeft();
Symbol rightSymbol = edge.getRight();
checkState(context.containsSymbol(leftSymbol));
checkState(context.containsSymbol(rightSymbol));
PlanNode left = context.getSymbolSource(leftSymbol);
PlanNode right = context.getSymbolSource(rightSymbol);
edges.put(left.getId(), new Edge(right, leftSymbol, rightSymbol));
edges.put(right.getId(), new Edge(left, rightSymbol, leftSymbol));
}
return new JoinGraph(nodes, edges.build(), newRoot, joinedFilters, Optional.empty());
}
private static class Builder
extends PlanVisitor<Context, JoinGraph>
{
@Override
protected JoinGraph visitPlan(PlanNode node, Context context)
{
for (PlanNode child : node.getSources()) {
JoinGraph graph = child.accept(this, context);
if (graph.size() < 2) {
continue;
}
context.addSubGraph(graph.withRootId(child.getId()));
}
for (Symbol symbol : node.getOutputSymbols()) {
context.setSymbolSource(symbol, node);
}
return new JoinGraph(node);
}
@Override
public JoinGraph visitFilter(FilterNode node, Context context)
{
JoinGraph graph = node.getSource().accept(this, context);
return graph.withFilter(node.getPredicate());
}
@Override
public JoinGraph visitJoin(JoinNode node, Context context)
{
//TODO: add support for non inner joins
if (node.getType() != INNER) {
return visitPlan(node, context);
}
JoinGraph left = node.getLeft().accept(this, context);
JoinGraph right = node.getRight().accept(this, context);
JoinGraph graph = left.joinWith(right, node.getCriteria(), context, node.getId());
if (node.getFilter().isPresent()) {
return graph.withFilter(node.getFilter().get());
}
return graph;
}
@Override
public JoinGraph visitProject(ProjectNode node, Context context)
{
if (node.isIdentity()) {
JoinGraph graph = node.getSource().accept(this, context);
return graph.withAssignments(node.getAssignments().getMap());
}
return visitPlan(node, context);
}
}
public static class Edge
{
private final PlanNode targetNode;
private final Symbol sourceSymbol;
private final Symbol targetSymbol;
public Edge(PlanNode targetNode, Symbol sourceSymbol, Symbol targetSymbol)
{
this.targetNode = requireNonNull(targetNode, "targetNode is null");
this.sourceSymbol = requireNonNull(sourceSymbol, "sourceSymbol is null");
this.targetSymbol = requireNonNull(targetSymbol, "targetSymbol is null");
}
public PlanNode getTargetNode()
{
return targetNode;
}
public Symbol getSourceSymbol()
{
return sourceSymbol;
}
public Symbol getTargetSymbol()
{
return targetSymbol;
}
}
private static class Context
{
private final Map<Symbol, PlanNode> symbolSources = new HashMap<>();
private final List<JoinGraph> joinGraphs = new ArrayList<>();
public void setSymbolSource(Symbol symbol, PlanNode node)
{
symbolSources.put(symbol, node);
}
public void addSubGraph(JoinGraph graph)
{
joinGraphs.add(graph);
}
public boolean containsSymbol(Symbol symbol)
{
return symbolSources.containsKey(symbol);
}
public PlanNode getSymbolSource(Symbol symbol)
{
checkState(containsSymbol(symbol));
return symbolSources.get(symbol);
}
public List<JoinGraph> getGraphs()
{
return joinGraphs;
}
}
}