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[CALCITE-2204] Use BFS for propagating cost #643

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[CALCITE-2204] Use BFS for propagating cost #643

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2c45cb8
[CALCITE-2204]Use BDF for propagating cost
LeoWangLZ Mar 5, 2018
f9bebed
[CALCITE-2204]Use ArrayDeque for propagating cost
LeoWangLZ Mar 5, 2018
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39 changes: 30 additions & 9 deletions core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,13 +32,15 @@
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.util.Litmus;
import org.apache.calcite.util.Pair;
import org.apache.calcite.util.Util;
import org.apache.calcite.util.trace.CalciteTrace;

import 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.Iterator;
Expand Down Expand Up @@ -319,15 +321,12 @@ RelNode buildCheapestPlan(VolcanoPlanner planner) {
*/
void propagateCostImprovements(VolcanoPlanner planner, RelMetadataQuery mq,
RelNode rel, Set<RelSubset> activeSet) {
for (RelSubset subset : set.subsets) {
if (rel.getTraitSet().satisfies(subset.traitSet)) {
subset.propagateCostImprovements0(planner, mq, rel, activeSet);
}
}
hierarchicalPropagateImprovement(planner, mq, this, rel, activeSet);
}

void propagateCostImprovements0(VolcanoPlanner planner, RelMetadataQuery mq,
RelNode rel, Set<RelSubset> activeSet) {
RelNode rel, Set<RelSubset> activeSet,
ArrayDeque<Pair<RelNode, RelSubset>> propagateQueue) {
++timestamp;

if (!activeSet.add(this)) {
Expand All @@ -340,7 +339,8 @@ void propagateCostImprovements0(VolcanoPlanner planner, RelMetadataQuery mq,
try {
final RelOptCost cost = planner.getCost(rel, mq);
if (cost.isLt(bestCost)) {
LOGGER.trace("Subset cost improved: subset [{}] cost was {} now {}", this, bestCost, cost);
LOGGER.trace("Subset cost improved: subset [{}] cost was {} now {}",
this, bestCost, cost);

bestCost = cost;
best = rel;
Expand All @@ -350,8 +350,7 @@ void propagateCostImprovements0(VolcanoPlanner planner, RelMetadataQuery mq,
planner.ruleQueue.recompute(this);
for (RelNode parent : getParents()) {
final RelSubset parentSubset = planner.getSubset(parent);
parentSubset.propagateCostImprovements(planner, mq, parent,
activeSet);
parentSubset.push(parent, propagateQueue);
}
planner.checkForSatisfiedConverters(set, rel);
}
Expand All @@ -360,6 +359,28 @@ void propagateCostImprovements0(VolcanoPlanner planner, RelMetadataQuery mq,
}
}

void hierarchicalPropagateImprovement(VolcanoPlanner planner, RelMetadataQuery mq,

@satybald satybald Apr 4, 2018

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@LeoWangLZ what do you think about documenting BFS approach with examples?

RelSubset subset, RelNode rel, Set<RelSubset> activeSet) {
ArrayDeque<Pair<RelNode, RelSubset>> propagateQueue = new ArrayDeque<>();
subset.push(rel, propagateQueue);

while (!propagateQueue.isEmpty()) {
Pair<RelNode, RelSubset> first = propagateQueue.remove();

first.getValue()
.propagateCostImprovements0(planner, mq, first.getKey(), activeSet,
propagateQueue);
}
}

void push(RelNode rel, ArrayDeque<Pair<RelNode, RelSubset>> propagateQueue) {
for (RelSubset subset : set.subsets) {
if (rel.getTraitSet().satisfies(subset.traitSet)) {
propagateQueue.add(Pair.of(rel, subset));
}
}
}

public void propagateBoostRemoval(VolcanoPlanner planner) {
planner.ruleQueue.recompute(this);

Expand Down