com.hazelcast.org.apache.calcite.plan.volcano.RelSubset Maven / Gradle / Ivy
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* this work for additional information regarding copyright ownership.
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* (the "License"); you may not use this file except in compliance with
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*
* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
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package com.hazelcast.org.apache.calcite.plan.volcano;
import com.hazelcast.org.apache.calcite.linq4j.Linq4j;
import com.hazelcast.org.apache.calcite.plan.RelOptCluster;
import com.hazelcast.org.apache.calcite.plan.RelOptCost;
import com.hazelcast.org.apache.calcite.plan.RelOptListener;
import com.hazelcast.org.apache.calcite.plan.RelOptPlanner;
import com.hazelcast.org.apache.calcite.plan.RelOptUtil;
import com.hazelcast.org.apache.calcite.plan.RelTrait;
import com.hazelcast.org.apache.calcite.plan.RelTraitSet;
import com.hazelcast.org.apache.calcite.rel.AbstractRelNode;
import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.RelWriter;
import com.hazelcast.org.apache.calcite.rel.core.CorrelationId;
import com.hazelcast.org.apache.calcite.rel.externalize.RelWriterImpl;
import com.hazelcast.org.apache.calcite.rel.metadata.RelMetadataQuery;
import com.hazelcast.org.apache.calcite.rel.type.RelDataType;
import com.hazelcast.org.apache.calcite.sql.SqlExplainLevel;
import com.hazelcast.org.apache.calcite.util.Litmus;
import com.hazelcast.org.apache.calcite.util.Pair;
import com.hazelcast.org.apache.calcite.util.Util;
import com.hazelcast.org.apache.calcite.util.trace.CalciteTrace;
import org.apiguardian.api.API;
import com.hazelcast.org.slf4j.Logger;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* Subset of an equivalence class where all relational expressions have the
* same physical properties.
*
* Physical properties are instances of the {@link RelTraitSet}, and consist
* of traits such as calling convention and collation (sort-order).
*
*
For some traits, a relational expression can have more than one instance.
* For example, R can be sorted on both [X] and [Y, Z]. In which case, R would
* belong to the sub-sets for [X] and [Y, Z]; and also the leading edges [Y] and
* [].
*
* @see RelNode
* @see RelSet
* @see RelTrait
*/
public class RelSubset extends AbstractRelNode {
//~ Static fields/initializers ---------------------------------------------
private static final Logger LOGGER = CalciteTrace.getPlannerTracer();
private static final int DELIVERED = 1;
private static final int REQUIRED = 2;
//~ Instance fields --------------------------------------------------------
/**
* Optimization task state
*/
OptimizeTask.State taskState;
/**
* cost of best known plan (it may have improved since)
*/
RelOptCost bestCost;
/**
* The set this subset belongs to.
*/
final RelSet set;
/**
* best known plan
*/
RelNode best;
/**
* Timestamp for metadata validity
*/
long timestamp;
/**
* Physical property state of current subset
* 0: logical operators, NONE convention is neither DELIVERED nor REQUIRED
* 1: traitSet DELIVERED from child operators or itself
* 2: traitSet REQUIRED from parent operators
* 3: both DELIVERED and REQUIRED
*/
private int state = 0;
/**
* This subset should trigger rules when it becomes delivered.
*/
boolean triggerRule = false;
//~ Constructors -----------------------------------------------------------
RelSubset(
RelOptCluster cluster,
RelSet set,
RelTraitSet traits) {
super(cluster, traits);
this.set = set;
assert traits.allSimple();
computeBestCost(cluster.getPlanner());
recomputeDigest();
}
//~ Methods ----------------------------------------------------------------
/**
* Computes the best {@link RelNode} in this subset.
*
*
Only necessary when a subset is created in a set that has subsets that
* subsume it. Rationale:
*
*
* - If the are no subsuming subsets, the subset is initially empty.
* - After creation, {@code best} and {@code bestCost} are maintained
* incrementally by {@link #propagateCostImprovements0} and
* {@link RelSet#mergeWith(VolcanoPlanner, RelSet)}.
*
*/
private void computeBestCost(RelOptPlanner planner) {
bestCost = planner.getCostFactory().makeInfiniteCost();
final RelMetadataQuery mq = getCluster().getMetadataQuery();
for (RelNode rel : getRels()) {
final RelOptCost cost = planner.getCost(rel, mq);
if (cost.isLt(bestCost)) {
bestCost = cost;
best = rel;
}
}
}
void setDelivered() {
triggerRule = !isDelivered();
state |= DELIVERED;
}
void setRequired() {
triggerRule = false;
state |= REQUIRED;
}
@API(since = "1.23", status = API.Status.EXPERIMENTAL)
public boolean isDelivered() {
return (state & DELIVERED) == DELIVERED;
}
@API(since = "1.23", status = API.Status.EXPERIMENTAL)
public boolean isRequired() {
return (state & REQUIRED) == REQUIRED;
}
public RelNode getBest() {
return best;
}
public RelNode getOriginal() {
return set.rel;
}
public RelNode copy(RelTraitSet traitSet, List inputs) {
if (inputs.isEmpty()) {
final RelTraitSet traitSet1 = traitSet.simplify();
if (traitSet1.equals(this.traitSet)) {
return this;
}
return set.getOrCreateSubset(getCluster(), traitSet1);
}
throw new UnsupportedOperationException();
}
public RelOptCost computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) {
return planner.getCostFactory().makeZeroCost();
}
public double estimateRowCount(RelMetadataQuery mq) {
if (best != null) {
return mq.getRowCount(best);
} else {
return mq.getRowCount(set.rel);
}
}
@Override public void explain(RelWriter pw) {
// Not a typical implementation of "explain". We don't gather terms &
// values to be printed later. We actually do the work.
pw.item("subset", toString());
final AbstractRelNode input =
(AbstractRelNode) Util.first(getBest(), getOriginal());
if (input == null) {
return;
}
input.explainTerms(pw);
pw.done(input);
}
@Override protected String computeDigest() {
StringBuilder digest = new StringBuilder("Subset#");
digest.append(set.id);
for (RelTrait trait : traitSet) {
digest.append('.').append(trait);
}
return digest.toString();
}
@Override protected RelDataType deriveRowType() {
return set.rel.getRowType();
}
/**
* Returns the collection of RelNodes one of whose inputs is in this
* subset.
*/
Set getParents() {
final Set list = new LinkedHashSet<>();
for (RelNode parent : set.getParentRels()) {
for (RelSubset rel : inputSubsets(parent)) {
// see usage of this method in propagateCostImprovements0()
if (rel == this) {
list.add(parent);
}
}
}
return list;
}
/**
* Returns the collection of distinct subsets that contain a RelNode one
* of whose inputs is in this subset.
*/
Set getParentSubsets(VolcanoPlanner planner) {
final Set list = new LinkedHashSet<>();
for (RelNode parent : set.getParentRels()) {
for (RelSubset rel : inputSubsets(parent)) {
if (rel.set == set && rel.getTraitSet().equals(traitSet)) {
list.add(planner.getSubset(parent));
}
}
}
return list;
}
private static List inputSubsets(RelNode parent) {
//noinspection unchecked
return (List) (List) parent.getInputs();
}
/**
* Returns a list of relational expressions one of whose children is this
* subset. The elements of the list are distinct.
*/
public Collection getParentRels() {
final Set list = new LinkedHashSet<>();
parentLoop:
for (RelNode parent : set.getParentRels()) {
for (RelSubset rel : inputSubsets(parent)) {
if (rel.set == set && traitSet.satisfies(rel.getTraitSet())) {
list.add(parent);
continue parentLoop;
}
}
}
return list;
}
RelSet getSet() {
return set;
}
/**
* Adds expression rel to this subset.
*/
void add(RelNode rel) {
if (set.rels.contains(rel)) {
return;
}
VolcanoPlanner planner = (VolcanoPlanner) rel.getCluster().getPlanner();
if (planner.getListener() != null) {
RelOptListener.RelEquivalenceEvent event =
new RelOptListener.RelEquivalenceEvent(
planner,
rel,
this,
true);
planner.getListener().relEquivalenceFound(event);
}
// If this isn't the first rel in the set, it must have compatible
// row type.
if (set.rel != null) {
RelOptUtil.equal("rowtype of new rel", rel.getRowType(),
"rowtype of set", getRowType(), Litmus.THROW);
}
set.addInternal(rel);
if (false) {
Set variablesSet = RelOptUtil.getVariablesSet(rel);
Set variablesStopped = rel.getVariablesSet();
Set variablesPropagated =
Util.minus(variablesSet, variablesStopped);
assert set.variablesPropagated.containsAll(variablesPropagated);
Set variablesUsed = RelOptUtil.getVariablesUsed(rel);
assert set.variablesUsed.containsAll(variablesUsed);
}
}
/**
* Recursively builds a tree consisting of the cheapest plan at each node.
*/
RelNode buildCheapestPlan(VolcanoPlanner planner) {
CheapestPlanReplacer replacer = new CheapestPlanReplacer(planner);
final RelNode cheapest = replacer.visit(this, -1, null);
if (planner.getListener() != null) {
RelOptListener.RelChosenEvent event =
new RelOptListener.RelChosenEvent(
planner,
null);
planner.getListener().relChosen(event);
}
return cheapest;
}
/**
* Checks whether a relexp has made its subset cheaper, and if it so,
* propagate new cost to parent rel nodes using breadth first manner.
*
* @param planner Planner
* @param mq Metadata query
* @param rel Relational expression whose cost has improved
* @param activeSet Set of active subsets, for cycle detection
*/
void propagateCostImprovements(VolcanoPlanner planner, RelMetadataQuery mq,
RelNode rel, Set activeSet) {
Queue> propagationQueue = new ArrayDeque<>();
for (RelSubset subset : set.subsets) {
if (rel.getTraitSet().satisfies(subset.traitSet)) {
propagationQueue.offer(Pair.of(subset, rel));
}
}
while (!propagationQueue.isEmpty()) {
Pair p = propagationQueue.poll();
p.left.propagateCostImprovements0(planner, mq, p.right, activeSet, propagationQueue);
}
}
void propagateCostImprovements0(VolcanoPlanner planner, RelMetadataQuery mq,
RelNode rel, Set activeSet,
Queue> propagationQueue) {
++timestamp;
if (!activeSet.add(this)) {
// This subset is already in the chain being propagated to. This
// means that the graph is cyclic, and therefore the cost of this
// relational expression - not this subset - must be infinite.
LOGGER.trace("cyclic: {}", this);
return;
}
try {
RelOptCost cost = planner.getCost(rel, mq);
// Update subset best cost when we find a cheaper rel or the current
// best's cost is changed
if (cost.isLt(bestCost)) {
LOGGER.trace("Subset cost changed: subset [{}] cost was {} now {}",
this, bestCost, cost);
bestCost = cost;
best = rel;
// since best was changed, cached metadata for this subset should be removed
mq.clearCache(this);
// Propagate cost change to parents
for (RelNode parent : getParents()) {
// removes parent cached metadata since its input was changed
mq.clearCache(parent);
final RelSubset parentSubset = planner.getSubset(parent);
// parent subset will clear its cache in propagateCostImprovements0 method itself
for (RelSubset subset : parentSubset.set.subsets) {
if (parent.getTraitSet().satisfies(subset.traitSet)) {
propagationQueue.offer(Pair.of(subset, parent));
}
}
}
}
} finally {
activeSet.remove(this);
}
}
@Override public void collectVariablesUsed(Set variableSet) {
variableSet.addAll(set.variablesUsed);
}
@Override public void collectVariablesSet(Set variableSet) {
variableSet.addAll(set.variablesPropagated);
}
/**
* Returns the rel nodes in this rel subset. All rels must have the same
* traits and are logically equivalent.
*
* @return all the rels in the subset
*/
public Iterable getRels() {
return () -> Linq4j.asEnumerable(set.rels)
.where(v1 -> v1.getTraitSet().satisfies(traitSet))
.iterator();
}
/**
* As {@link #getRels()} but returns a list.
*/
public List getRelList() {
final List list = new ArrayList<>();
for (RelNode rel : set.rels) {
if (rel.getTraitSet().satisfies(traitSet)) {
list.add(rel);
}
}
return list;
}
/**
* Returns stream of subsets whose traitset satisfies
* current subset's traitset.
*/
@API(since = "1.23", status = API.Status.EXPERIMENTAL)
public Stream getSubsetsSatisfyingThis() {
return set.subsets.stream()
.filter(s -> s.getTraitSet().satisfies(traitSet));
}
/**
* Returns stream of subsets whose traitset is satisfied
* by current subset's traitset.
*/
@API(since = "1.23", status = API.Status.EXPERIMENTAL)
public Stream getSatisfyingSubsets() {
return set.subsets.stream()
.filter(s -> traitSet.satisfies(s.getTraitSet()));
}
//~ Inner Classes ----------------------------------------------------------
/**
* Identifies the leaf-most non-implementable nodes.
*/
static class DeadEndFinder {
final Set deadEnds = new HashSet<>();
// To save time
private final Set visitedNodes = new HashSet<>();
// For cycle detection
private final Set activeNodes = new HashSet<>();
private boolean visit(RelNode p) {
if (p instanceof RelSubset) {
visitSubset((RelSubset) p);
return false;
}
return visitRel(p);
}
private void visitSubset(RelSubset subset) {
RelNode cheapest = subset.getBest();
if (cheapest != null) {
// Subset is implementable, and we are looking for bad ones, so stop here
return;
}
boolean isEmpty = true;
for (RelNode rel : subset.getRels()) {
if (rel instanceof AbstractConverter) {
// Converters are not implementable
continue;
}
if (!activeNodes.add(rel)) {
continue;
}
boolean res = visit(rel);
isEmpty &= res;
activeNodes.remove(rel);
}
if (isEmpty) {
deadEnds.add(subset);
}
}
/**
* Returns true when input {@code RelNode} is cyclic.
*/
private boolean visitRel(RelNode p) {
// If one of the inputs is in "active" set, that means the rel forms a cycle,
// then we just ignore it. Cyclic rels are not implementable.
for (RelNode oldInput : p.getInputs()) {
if (activeNodes.contains(oldInput)) {
return true;
}
}
// The same subset can be used multiple times (e.g. union all with the same inputs),
// so it is important to perform "contains" and "add" in different loops
activeNodes.addAll(p.getInputs());
for (RelNode oldInput : p.getInputs()) {
if (!visitedNodes.add(oldInput)) {
// We don't want to explore the same subset twice
continue;
}
visit(oldInput);
}
activeNodes.removeAll(p.getInputs());
return false;
}
}
/**
* Visitor which walks over a tree of {@link RelSet}s, replacing each node
* with the cheapest implementation of the expression.
*/
static class CheapestPlanReplacer {
VolcanoPlanner planner;
CheapestPlanReplacer(VolcanoPlanner planner) {
super();
this.planner = planner;
}
private static String traitDiff(RelTraitSet original, RelTraitSet desired) {
return Pair.zip(original, desired)
.stream()
.filter(p -> !p.left.satisfies(p.right))
.map(p -> p.left.getTraitDef().getSimpleName() + ": " + p.left + " -> " + p.right)
.collect(Collectors.joining(", ", "[", "]"));
}
public RelNode visit(
RelNode p,
int ordinal,
RelNode parent) {
if (p instanceof RelSubset) {
RelSubset subset = (RelSubset) p;
RelNode cheapest = subset.best;
if (cheapest == null) {
// Dump the planner's expression pool so we can figure
// out why we reached impasse.
StringWriter sw = new StringWriter();
final PrintWriter pw = new PrintWriter(sw);
pw.print("There are not enough rules to produce a node with desired properties");
RelTraitSet desiredTraits = subset.getTraitSet();
String sep = ": ";
for (RelTrait trait : desiredTraits) {
pw.print(sep);
pw.print(trait.getTraitDef().getSimpleName());
pw.print("=");
pw.print(trait);
sep = ", ";
}
pw.print(".");
DeadEndFinder finder = new DeadEndFinder();
finder.visit(subset);
if (finder.deadEnds.isEmpty()) {
pw.print(" All the inputs have relevant nodes, however the cost is still infinite.");
} else {
Map problemCounts =
finder.deadEnds.stream()
.filter(deadSubset -> deadSubset.getOriginal() != null)
.map(x -> x.getOriginal().getClass().getSimpleName()
+ traitDiff(x.getOriginal().getTraitSet(), x.getTraitSet()))
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
// Sort problems from most often to less often ones
String problems = problemCounts.entrySet().stream()
.sorted(Comparator.comparingLong(Map.Entry::getValue).reversed())
.map(e -> e.getKey() + (e.getValue() > 1 ? " (" + e.getValue() + " cases)" : ""))
.collect(Collectors.joining(", "));
pw.println();
pw.print("Missing conversion");
pw.print(finder.deadEnds.size() == 1 ? " is " : "s are ");
pw.print(problems);
pw.println();
if (finder.deadEnds.size() == 1) {
pw.print("There is 1 empty subset: ");
}
if (finder.deadEnds.size() > 1) {
pw.println("There are " + finder.deadEnds.size() + " empty subsets:");
}
int i = 0;
int rest = finder.deadEnds.size();
for (RelSubset deadEnd : finder.deadEnds) {
if (finder.deadEnds.size() > 1) {
pw.print("Empty subset ");
pw.print(i);
pw.print(": ");
}
pw.print(deadEnd);
pw.println(", the relevant part of the original plan is as follows");
RelNode original = deadEnd.getOriginal();
original.explain(
new RelWriterImpl(pw, SqlExplainLevel.EXPPLAN_ATTRIBUTES, true));
i++;
rest--;
if (rest > 0) {
pw.println();
}
if (i >= 10 && rest > 1) {
pw.print("The rest ");
pw.print(rest);
pw.println(" leafs are omitted.");
break;
}
}
}
pw.println();
planner.dump(pw);
pw.flush();
final String dump = sw.toString();
RuntimeException e =
new RelOptPlanner.CannotPlanException(dump);
LOGGER.trace("Caught exception in class={}, method=visit", getClass().getName(), e);
throw e;
}
p = cheapest;
}
if (ordinal != -1) {
if (planner.getListener() != null) {
RelOptListener.RelChosenEvent event =
new RelOptListener.RelChosenEvent(
planner,
p);
planner.getListener().relChosen(event);
}
}
List oldInputs = p.getInputs();
List inputs = new ArrayList<>();
for (int i = 0; i < oldInputs.size(); i++) {
RelNode oldInput = oldInputs.get(i);
RelNode input = visit(oldInput, i, p);
inputs.add(input);
}
if (!inputs.equals(oldInputs)) {
final RelNode pOld = p;
p = p.copy(p.getTraitSet(), inputs);
planner.provenanceMap.put(
p, new VolcanoPlanner.DirectProvenance(pOld));
}
return p;
}
}
}
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