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[enhancement](Nereids) make stats unchanged (#23737)

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make stats unchanged when explore plan
This commit is contained in:
谢健
2023-09-14 22:18:54 +08:00
committed by GitHub
parent 66bd2a4862
commit 5ba1f62da8
29 changed files with 320 additions and 321 deletions
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17
fe/fe-core/src/main/java/org/apache/doris/nereids/stats/StatsCalculator.java
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@ -222,22 +222,13 @@ public class StatsCalculator extends DefaultPlanVisitor<Statistics, Void> {
private void estimate() {
Plan plan = groupExpression.getPlan();
Statistics newStats = plan.accept(this, null);
Statistics oldStats = groupExpression.getOwnerGroup().getStatistics();
/*
in an ideal cost model, every group expression in a group are equivalent, but in fact the cost are different.
we record the lowest expression cost as group cost to avoid missing this group.
*/
if (oldStats == null) {
// We ensure that the rowCount remains unchanged in order to make the cost of each plan comparable.
if (groupExpression.getOwnerGroup().getStatistics() == null) {
groupExpression.getOwnerGroup().setStatistics(newStats);
groupExpression.setEstOutputRowCount(newStats.getRowCount());
} else {
Statistics discardStats = newStats;
if (oldStats.getRowCount() > newStats.getRowCount()) {
groupExpression.getOwnerGroup().setStatistics(newStats);
discardStats = oldStats;
}
groupExpression.getOwnerGroup().getStatistics().updateNdv(discardStats);
groupExpression.getOwnerGroup().getStatistics().updateNdv(newStats);
}
groupExpression.setEstOutputRowCount(newStats.getRowCount());
groupExpression.setStatDerived(true);
}