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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you 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.hazelcast.org.apache.calcite.plan;
import com.hazelcast.org.apache.calcite.config.CalciteSystemProperty;
import com.hazelcast.org.apache.calcite.plan.hep.HepPlanner;
import com.hazelcast.org.apache.calcite.plan.hep.HepProgram;
import com.hazelcast.org.apache.calcite.plan.hep.HepProgramBuilder;
import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.core.RelFactories;
import com.hazelcast.org.apache.calcite.rel.rules.CoreRules;
import com.hazelcast.org.apache.calcite.sql2rel.RelFieldTrimmer;
import com.hazelcast.org.apache.calcite.tools.RelBuilder;
import com.hazelcast.org.apache.calcite.util.Pair;
import com.hazelcast.org.apache.calcite.util.Util;
import com.hazelcast.org.apache.calcite.util.graph.DefaultDirectedGraph;
import com.hazelcast.org.apache.calcite.util.graph.DefaultEdge;
import com.hazelcast.org.apache.calcite.util.graph.DirectedGraph;
import com.hazelcast.org.apache.calcite.util.graph.Graphs;
import com.hazelcast.org.apache.calcite.util.graph.TopologicalOrderIterator;
import com.hazelcast.com.google.common.base.Suppliers;
import com.hazelcast.com.google.common.collect.ImmutableList;
import com.hazelcast.com.google.common.collect.Sets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Supplier;
/**
* Utility methods for using
* materialized views and lattices for queries.
*/
public abstract class RelOptMaterializations {
/**
* Returns a list of RelNode transformed from all possible combination of
* materialized view uses. Big queries will likely have more than one
* transformed RelNode, e.g., (t1 group by c1) join (t2 group by c2).
* @param rel the original RelNode
* @param materializations the materialized view list
* @return the list of transformed RelNode together with their corresponding
* materialized views used in the transformation.
*/
public static List>> useMaterializedViews(
final RelNode rel, List materializations) {
return useMaterializedViews(rel, materializations, SubstitutionVisitor.DEFAULT_RULES);
}
/**
* Returns a list of RelNode transformed from all possible combination of
* materialized view uses. Big queries will likely have more than one
* transformed RelNode, e.g., (t1 group by c1) join (t2 group by c2).
* In addition, you can add custom materialized view recognition rules.
* @param rel the original RelNode
* @param materializations the materialized view list
* @param materializationRules the materialized view recognition rules
* @return the list of transformed RelNode together with their corresponding
* materialized views used in the transformation.
*/
public static List>> useMaterializedViews(
final RelNode rel, List materializations,
List materializationRules) {
final List applicableMaterializations =
getApplicableMaterializations(rel, materializations);
final List>> applied =
new ArrayList<>();
applied.add(Pair.of(rel, ImmutableList.of()));
for (RelOptMaterialization m : applicableMaterializations) {
int count = applied.size();
for (int i = 0; i < count; i++) {
Pair> current = applied.get(i);
List sub = substitute(current.left, m, materializationRules);
if (!sub.isEmpty()) {
ImmutableList.Builder builder =
ImmutableList.builder();
builder.addAll(current.right);
builder.add(m);
List uses = builder.build();
for (RelNode rel2 : sub) {
applied.add(Pair.of(rel2, uses));
}
}
}
}
return applied.subList(1, applied.size());
}
/**
* Returns a list of RelNode transformed from all possible lattice uses.
* @param rel the original RelNode
* @param lattices the lattice list
* @return the list of transformed RelNode together with their corresponding
* lattice used in the transformation.
*/
public static List> useLattices(
final RelNode rel, List lattices) {
final Set queryTables = RelOptUtil.findTables(rel);
// Use a lattice if the query uses at least the central (fact) table of the
// lattice.
final List> latticeUses = new ArrayList<>();
final Set> queryTableNames =
Sets.newHashSet(
Util.transform(queryTables, RelOptTable::getQualifiedName));
// Remember leaf-join form of root so we convert at most once.
final Supplier leafJoinRoot =
Suppliers.memoize(() -> RelOptMaterialization.toLeafJoinForm(rel))::get;
for (RelOptLattice lattice : lattices) {
if (queryTableNames.contains(lattice.rootTable().getQualifiedName())) {
RelNode rel2 = lattice.rewrite(leafJoinRoot.get());
if (rel2 != null) {
if (CalciteSystemProperty.DEBUG.value()) {
System.out.println("use lattice:\n"
+ RelOptUtil.toString(rel2));
}
latticeUses.add(Pair.of(rel2, lattice));
}
}
}
return latticeUses;
}
/**
* Returns a list of materializations that can potentially be used by the query.
*/
public static List getApplicableMaterializations(
RelNode rel, List materializations) {
DirectedGraph, DefaultEdge> usesGraph =
DefaultDirectedGraph.create();
final Map, RelOptMaterialization> qnameMap = new HashMap<>();
for (RelOptMaterialization materialization : materializations) {
// If materialization is a tile in a lattice, we will deal with it shortly.
if (materialization.qualifiedTableName != null
&& materialization.starTable == null) {
final List qname = materialization.qualifiedTableName;
qnameMap.put(qname, materialization);
for (RelOptTable usedTable
: RelOptUtil.findTables(materialization.queryRel)) {
usesGraph.addVertex(qname);
usesGraph.addVertex(usedTable.getQualifiedName());
usesGraph.addEdge(usedTable.getQualifiedName(), qname);
}
}
}
// Use a materialization if uses at least one of the tables are used by
// the query. (Simple rule that includes some materializations we won't
// actually use.)
// For example, given materializations:
// T = Emps Join Depts
// T2 = T Group by C1
// the graph will contain
// (T, Emps), (T, Depts), (T2, T)
// and therefore we can deduce T2 uses Emps.
final Graphs.FrozenGraph, DefaultEdge> frozenGraph =
Graphs.makeImmutable(usesGraph);
final Set queryTablesUsed = RelOptUtil.findTables(rel);
final List applicableMaterializations =
new ArrayList<>();
for (List qname : TopologicalOrderIterator.of(usesGraph)) {
RelOptMaterialization materialization = qnameMap.get(qname);
if (materialization != null
&& usesTable(materialization.qualifiedTableName, queryTablesUsed, frozenGraph)) {
applicableMaterializations.add(materialization);
}
}
return applicableMaterializations;
}
private static List substitute(
RelNode root, RelOptMaterialization materialization,
List materializationRules) {
// First, if the materialization is in terms of a star table, rewrite
// the query in terms of the star table.
if (materialization.starRelOptTable != null) {
RelNode newRoot = RelOptMaterialization.tryUseStar(root,
materialization.starRelOptTable);
if (newRoot != null) {
root = newRoot;
}
}
// Push filters to the bottom, and combine projects on top.
RelNode target = materialization.queryRel;
// try to trim unused field in relational expressions.
root = trimUnusedfields(root);
target = trimUnusedfields(target);
HepProgram program =
new HepProgramBuilder()
.addRuleInstance(CoreRules.FILTER_PROJECT_TRANSPOSE)
.addRuleInstance(CoreRules.FILTER_MERGE)
.addRuleInstance(CoreRules.FILTER_INTO_JOIN)
.addRuleInstance(CoreRules.JOIN_CONDITION_PUSH)
.addRuleInstance(CoreRules.FILTER_AGGREGATE_TRANSPOSE)
.addRuleInstance(CoreRules.PROJECT_MERGE)
.addRuleInstance(CoreRules.PROJECT_REMOVE)
.addRuleInstance(CoreRules.PROJECT_JOIN_TRANSPOSE)
.addRuleInstance(CoreRules.PROJECT_SET_OP_TRANSPOSE)
.addRuleInstance(CoreRules.AGGREGATE_PROJECT_PULL_UP_CONSTANTS)
.addRuleInstance(CoreRules.FILTER_TO_CALC)
.addRuleInstance(CoreRules.PROJECT_TO_CALC)
.addRuleInstance(CoreRules.FILTER_CALC_MERGE)
.addRuleInstance(CoreRules.PROJECT_CALC_MERGE)
.addRuleInstance(CoreRules.CALC_MERGE)
.build();
// We must use the same HEP planner for the two optimizations below.
// Thus different nodes with the same digest will share the same vertex in
// the plan graph. This is important for the matching process.
final HepPlanner hepPlanner = new HepPlanner(program);
hepPlanner.setRoot(target);
target = hepPlanner.findBestExp();
hepPlanner.setRoot(root);
root = hepPlanner.findBestExp();
return new SubstitutionVisitor(target, root, ImmutableList.
builder()
.addAll(materializationRules)
.build()).go(materialization.tableRel);
}
/**
* Trim unused fields in relational expressions.
*/
private static RelNode trimUnusedfields(RelNode relNode) {
final List relOptTables = RelOptUtil.findAllTables(relNode);
RelOptSchema relOptSchema = null;
if (relOptTables.size() != 0) {
relOptSchema = relOptTables.get(0).getRelOptSchema();
}
final RelBuilder relBuilder = RelFactories.LOGICAL_BUILDER.create(
relNode.getCluster(), relOptSchema);
final RelFieldTrimmer relFieldTrimmer = new RelFieldTrimmer(null, relBuilder);
final RelNode rel = relFieldTrimmer.trim(relNode);
return rel;
}
/**
* Returns whether {@code table} uses one or more of the tables in
* {@code usedTables}.
*/
private static boolean usesTable(
List qualifiedName,
Set usedTables,
Graphs.FrozenGraph, DefaultEdge> usesGraph) {
for (RelOptTable queryTable : usedTables) {
if (usesGraph.getShortestDistance(queryTable.getQualifiedName(), qualifiedName)
!= -1) {
return true;
}
}
return false;
}
}
