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[refactor](Nereids): avoid useless groupByColStats Map (#22000)

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This commit is contained in:
jakevin
2023-07-24 12:13:52 +08:00
committed by GitHub
parent ea35437c44
commit 66fa1bef6d
1 changed files with 24 additions and 26 deletions
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50
fe/fe-core/src/main/java/org/apache/doris/nereids/stats/StatsCalculator.java
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@ -130,8 +130,8 @@ import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@ -689,38 +689,36 @@ public class StatsCalculator extends DefaultPlanVisitor<Statistics, Void> {
private double estimateGroupByRowCount(List<Expression> groupByExpressions, Statistics childStats) {
double rowCount = 1;
Map<Expression, ColumnStatistic> groupByColStats = new HashMap<>();
// if there is group-bys, output row count is childStats.getRowCount() * DEFAULT_AGGREGATE_RATIO,
// o.w. output row count is 1
// example: select sum(A) from T;
if (groupByExpressions.isEmpty()) {
return 1;
}
List<Double> groupByNdvs = new ArrayList<>();
for (Expression groupByExpr : groupByExpressions) {
ColumnStatistic colStats = childStats.findColumnStatistics(groupByExpr);
if (colStats == null) {
colStats = ExpressionEstimation.estimate(groupByExpr, childStats);
}
groupByColStats.put(groupByExpr, colStats);
}
int groupByCount = groupByExpressions.size();
if (groupByColStats.values().stream().anyMatch(ColumnStatistic::isUnKnown)) {
// if there is group-bys, output row count is childStats.getRowCount() * DEFAULT_AGGREGATE_RATIO,
// o.w. output row count is 1
// example: select sum(A) from T;
if (groupByCount > 0) {
if (colStats.isUnKnown()) {
rowCount = childStats.getRowCount() * DEFAULT_AGGREGATE_RATIO;
} else {
rowCount = 1;
rowCount = Math.max(1, rowCount);
rowCount = Math.min(rowCount, childStats.getRowCount());
return rowCount;
}
} else {
if (groupByCount > 0) {
List<Double> groupByNdvs = groupByColStats.values().stream()
.map(colStats -> colStats.ndv)
.sorted(Comparator.reverseOrder()).collect(Collectors.toList());
rowCount = groupByNdvs.get(0);
for (int groupByIndex = 1; groupByIndex < groupByCount; ++groupByIndex) {
rowCount *= Math.max(1, groupByNdvs.get(groupByIndex) * Math.pow(
AGGREGATE_COLUMN_CORRELATION_COEFFICIENT, groupByIndex + 1D));
if (rowCount > childStats.getRowCount()) {
rowCount = childStats.getRowCount();
break;
}
}
double ndv = colStats.ndv;
groupByNdvs.add(ndv);
}
groupByNdvs.sort(Collections.reverseOrder());
rowCount = groupByNdvs.get(0);
for (int groupByIndex = 1; groupByIndex < groupByExpressions.size(); ++groupByIndex) {
rowCount *= Math.max(1, groupByNdvs.get(groupByIndex) * Math.pow(
AGGREGATE_COLUMN_CORRELATION_COEFFICIENT, groupByIndex + 1D));
if (rowCount > childStats.getRowCount()) {
rowCount = childStats.getRowCount();
break;
}
}
rowCount = Math.max(1, rowCount);