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Query planner refactor 1 (typedb#5087)
## What is the goal of this PR? Begin cleaning up very procedural and overly generic code in Query Planner to be more understandible. ## What are the changes implemented in this PR? * Remove Generic from `DirectedEdge<T>` and all associated classes, including tests. Usage was early exclusively `DirectedEdge<Node>`. Now none of the classes in the Query Planner accept a generic. It seems like the generic originally existed to allow using an Integer as a Node, rather than a Node object in tests - tests for now use `Node` with the Integer encoded as a variable string. * `Node` had methods `addIfPresent(a, b, allNodes)`, which did a create-if-present in the `allNodes` map and returned the Node. This functionality is moved out. * `NodeId` now uses a factory constructor because the instances are not meant to be unique * Move a large chunk of isolated code from `GreedyTraversalPlan.java` into `RelationTypeInference.java` - all to do with inferring types from role players to generate more Label fragments. * `Fragment`s provide the `Node`s that go into the internal QueryPlanner traversal graph - Fragments that represent Janus edges for instance provide a `middle` node that is not a valid starting point. These are collected into the set of all Nodes at the start of query planning now rather than deep in the chain of c-like function calls. * Move chunks of code into their own methods to deal with later (`chooseStartingNodes`, `buildDependenciesBetweenNodes`) * _important_ experimental change to NOT access all the indexed vertices first thing in the query plan - do them as a normal step in the flattened minimum spanning tree as required (starting point is still almost always an indexed vertex) * Remove `lowPriorityStartingNodes` as we currently always reify nodes, so implicit relationships are as good of a starting point as any
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| /* | ||
| * GRAKN.AI - THE KNOWLEDGE GRAPH | ||
| * Copyright (C) 2018 Grakn Labs Ltd | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU Affero General Public License as | ||
| * published by the Free Software Foundation, either version 3 of the | ||
| * License, or (at your option) any later version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU Affero General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU Affero General Public License | ||
| * along with this program. If not, see <https://www.gnu.org/licenses/>. | ||
| */ | ||
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| package grakn.core.graql.gremlin; | ||
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| import com.google.common.collect.HashMultimap; | ||
| import com.google.common.collect.ImmutableSet; | ||
| import com.google.common.collect.Iterators; | ||
| import com.google.common.collect.Multimap; | ||
| import com.google.common.collect.Sets; | ||
| import grakn.core.concept.Label; | ||
| import grakn.core.concept.type.RelationType; | ||
| import grakn.core.concept.type.Role; | ||
| import grakn.core.concept.type.SchemaConcept; | ||
| import grakn.core.concept.type.Type; | ||
| import grakn.core.graql.gremlin.fragment.Fragment; | ||
| import grakn.core.graql.gremlin.fragment.Fragments; | ||
| import grakn.core.graql.gremlin.fragment.InIsaFragment; | ||
| import grakn.core.graql.gremlin.fragment.InSubFragment; | ||
| import grakn.core.graql.gremlin.fragment.LabelFragment; | ||
| import grakn.core.graql.gremlin.fragment.OutRolePlayerFragment; | ||
| import grakn.core.graql.gremlin.sets.EquivalentFragmentSets; | ||
| import grakn.core.server.session.TransactionOLTP; | ||
| import graql.lang.property.IsaProperty; | ||
| import graql.lang.property.TypeProperty; | ||
| import graql.lang.statement.Statement; | ||
| import graql.lang.statement.Variable; | ||
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| import java.util.Collection; | ||
| import java.util.Collections; | ||
| import java.util.HashMap; | ||
| import java.util.HashSet; | ||
| import java.util.Iterator; | ||
| import java.util.Map; | ||
| import java.util.Set; | ||
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| import static graql.lang.Graql.var; | ||
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| public class RelationTypeInference { | ||
| // infer type of relation type if we know the type of the role players | ||
| // add label fragment and isa fragment if we can infer any | ||
| public static Set<Fragment> inferRelationTypes(TransactionOLTP tx, Set<Fragment> allFragments) { | ||
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| Set<Fragment> inferredFragments = new HashSet<>(); | ||
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| Map<Variable, Type> labelVarTypeMap = getLabelVarTypeMap(tx, allFragments); | ||
| if (labelVarTypeMap.isEmpty()) return inferredFragments; | ||
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| Multimap<Variable, Type> instanceVarTypeMap = getInstanceVarTypeMap(allFragments, labelVarTypeMap); | ||
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| Multimap<Variable, Variable> relationRolePlayerMap = getRelationRolePlayerMap(allFragments, instanceVarTypeMap); | ||
| if (relationRolePlayerMap.isEmpty()) return inferredFragments; | ||
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| // for each type, get all possible relation type it could be in | ||
| Multimap<Type, RelationType> relationMap = HashMultimap.create(); | ||
| labelVarTypeMap.values().stream().distinct().forEach( | ||
| type -> addAllPossibleRelations(relationMap, type)); | ||
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| // inferred labels should be kept separately, even if they are already in allFragments set | ||
| Map<Label, Statement> inferredLabels = new HashMap<>(); | ||
| relationRolePlayerMap.asMap().forEach((relationVar, rolePlayerVars) -> { | ||
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| Set<Type> possibleRelationTypes = rolePlayerVars.stream() | ||
| .filter(instanceVarTypeMap::containsKey) | ||
| .map(rolePlayer -> getAllPossibleRelationTypes( | ||
| instanceVarTypeMap.get(rolePlayer), relationMap)) | ||
| .reduce(Sets::intersection).orElse(Collections.emptySet()); | ||
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| //TODO: if possibleRelationTypes here is empty, the query will not match any data | ||
| if (possibleRelationTypes.size() == 1) { | ||
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| Type relationType = possibleRelationTypes.iterator().next(); | ||
| Label label = relationType.label(); | ||
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| // add label fragment if this label has not been inferred | ||
| if (!inferredLabels.containsKey(label)) { | ||
| Statement labelVar = var(); | ||
| inferredLabels.put(label, labelVar); | ||
| Fragment labelFragment = Fragments.label(new TypeProperty(label.getValue()), labelVar.var(), ImmutableSet.of(label)); | ||
| inferredFragments.add(labelFragment); | ||
| } | ||
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| // finally, add inferred isa fragments | ||
| Statement labelVar = inferredLabels.get(label); | ||
| IsaProperty isaProperty = new IsaProperty(labelVar); | ||
| EquivalentFragmentSet isaEquivalentFragmentSet = EquivalentFragmentSets.isa(isaProperty, | ||
| relationVar, labelVar.var(), relationType.isImplicit()); | ||
| inferredFragments.addAll(isaEquivalentFragmentSet.fragments()); | ||
| } | ||
| }); | ||
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| return inferredFragments; | ||
| } | ||
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| // find all vars with direct or indirect out isa edges | ||
| private static Multimap<Variable, Type> getInstanceVarTypeMap( | ||
| Set<Fragment> allFragments, Map<Variable, Type> labelVarTypeMap) { | ||
| Multimap<Variable, Type> instanceVarTypeMap = HashMultimap.create(); | ||
| int oldSize; | ||
| do { | ||
| oldSize = instanceVarTypeMap.size(); | ||
| allFragments.stream() | ||
| .filter(fragment -> labelVarTypeMap.containsKey(fragment.start())) // restrict to types | ||
| .filter(fragment -> fragment instanceof InIsaFragment || fragment instanceof InSubFragment) // | ||
| .forEach(fragment -> instanceVarTypeMap.put(fragment.end(), labelVarTypeMap.get(fragment.start()))); | ||
| } while (oldSize != instanceVarTypeMap.size()); | ||
| return instanceVarTypeMap; | ||
| } | ||
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| // find all vars representing types | ||
| private static Map<Variable, Type> getLabelVarTypeMap(TransactionOLTP tx, Set<Fragment> allFragments) { | ||
| Map<Variable, Type> labelVarTypeMap = new HashMap<>(); | ||
| allFragments.stream() | ||
| .filter(LabelFragment.class::isInstance) | ||
| .forEach(fragment -> { | ||
| // TODO: labels() should return ONE label instead of a set | ||
| SchemaConcept schemaConcept = tx.getSchemaConcept( | ||
| Iterators.getOnlyElement(((LabelFragment) fragment).labels().iterator())); | ||
| if (schemaConcept != null && !schemaConcept.isRole() && !schemaConcept.isRule()) { | ||
| labelVarTypeMap.put(fragment.start(), schemaConcept.asType()); | ||
| } | ||
| }); | ||
| return labelVarTypeMap; | ||
| } | ||
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| private static Multimap<Variable, Variable> getRelationRolePlayerMap( | ||
| Set<Fragment> allFragments, Multimap<Variable, Type> instanceVarTypeMap) { | ||
| // relation vars and its role player vars | ||
| Multimap<Variable, Variable> relationRolePlayerMap = HashMultimap.create(); | ||
| allFragments.stream().filter(OutRolePlayerFragment.class::isInstance) | ||
| .forEach(fragment -> relationRolePlayerMap.put(fragment.start(), fragment.end())); | ||
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| // find all the relation requiring type inference | ||
| Iterator<Variable> iterator = relationRolePlayerMap.keySet().iterator(); | ||
| while (iterator.hasNext()) { | ||
| Variable relation = iterator.next(); | ||
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| // the relation should have at least 2 known role players so we can infer something useful | ||
| if (instanceVarTypeMap.containsKey(relation) || | ||
| relationRolePlayerMap.get(relation).size() < 2) { | ||
| iterator.remove(); | ||
| } else { | ||
| int numRolePlayersHaveType = 0; | ||
| for (Variable rolePlayer : relationRolePlayerMap.get(relation)) { | ||
| if (instanceVarTypeMap.containsKey(rolePlayer)) { | ||
| numRolePlayersHaveType++; | ||
| } | ||
| } | ||
| if (numRolePlayersHaveType < 2) { | ||
| iterator.remove(); | ||
| } | ||
| } | ||
| } | ||
| return relationRolePlayerMap; | ||
| } | ||
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| private static void addAllPossibleRelations(Multimap<Type, RelationType> relationMap, Type metaType) { | ||
| metaType.subs().forEach(type -> type.playing().flatMap(Role::relations) | ||
| .forEach(relationType -> relationMap.put(type, relationType))); | ||
| } | ||
|
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| private static Set<Type> getAllPossibleRelationTypes( | ||
| Collection<Type> instanceVarTypes, Multimap<Type, RelationType> relationMap) { | ||
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| return instanceVarTypes.stream() | ||
| .map(rolePlayerType -> (Set<Type>) new HashSet<Type>(relationMap.get(rolePlayerType))) | ||
| .reduce(Sets::intersection).orElse(Collections.emptySet()); | ||
| } | ||
| } |
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