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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 org.apache.drill.exec.planner.cost;
import java.util.ArrayList;
import java.util.List;
import org.apache.calcite.plan.RelOptUtil;
import org.apache.calcite.plan.volcano.RelSubset;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.JoinRelType;
import org.apache.calcite.rel.core.TableScan;
import org.apache.calcite.rel.metadata.ReflectiveRelMetadataProvider;
import org.apache.calcite.rel.metadata.RelMdSelectivity;
import org.apache.calcite.rel.metadata.RelMdUtil;
import org.apache.calcite.rel.metadata.RelMetadataProvider;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.rex.RexBuilder;
import org.apache.calcite.rex.RexCall;
import org.apache.calcite.rex.RexInputRef;
import org.apache.calcite.rex.RexNode;
import org.apache.calcite.rex.RexUtil;
import org.apache.calcite.rex.RexVisitor;
import org.apache.calcite.rex.RexVisitorImpl;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.util.BuiltInMethod;
import org.apache.calcite.util.Util;
import org.apache.drill.common.expression.SchemaPath;
import org.apache.drill.exec.physical.base.DbGroupScan;
import org.apache.drill.exec.physical.base.GroupScan;
import org.apache.drill.exec.planner.common.DrillJoinRelBase;
import org.apache.drill.exec.planner.common.DrillRelOptUtil;
import org.apache.drill.exec.planner.common.DrillScanRelBase;
import org.apache.drill.exec.planner.logical.DrillScanRel;
import org.apache.drill.exec.planner.logical.DrillTable;
import org.apache.drill.exec.planner.logical.DrillTranslatableTable;
import org.apache.drill.exec.planner.physical.PlannerSettings;
import org.apache.drill.exec.planner.physical.PrelUtil;
import org.apache.drill.exec.planner.physical.ScanPrel;
public class DrillRelMdSelectivity extends RelMdSelectivity {
private static final DrillRelMdSelectivity INSTANCE = new DrillRelMdSelectivity();
static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(DrillRelMdSelectivity.class);
public static final RelMetadataProvider SOURCE = ReflectiveRelMetadataProvider.reflectiveSource(BuiltInMethod.SELECTIVITY.method, INSTANCE);
@Override
public Double getSelectivity(RelNode rel, RelMetadataQuery mq, RexNode predicate) {
if (rel instanceof RelSubset && !DrillRelOptUtil.guessRows(rel)) {
return getSubsetSelectivity((RelSubset) rel, mq, predicate);
} else if (rel instanceof TableScan) {
return getScanSelectivity(rel, mq, predicate);
} else if (rel instanceof DrillJoinRelBase) {
return getJoinSelectivity(((DrillJoinRelBase) rel), mq, predicate);
} /*else if (rel instanceof SingleRel && !DrillRelOptUtil.guessRows(rel)) {
return getSelectivity(((SingleRel)rel).getInput(), mq, predicate);
}*/ else {
return super.getSelectivity(rel, mq, predicate);
}
}
private Double getSubsetSelectivity(RelSubset rel, RelMetadataQuery mq, RexNode predicate) {
if (rel.getBest() != null) {
return getSelectivity(rel.getBest(), mq, predicate);
} else {
List<RelNode> list = rel.getRelList();
if (list != null && list.size() > 0) {
return getSelectivity(list.get(0), mq, predicate);
}
}
//TODO: Not required? return mq.getSelectivity(((RelSubset)rel).getOriginal(), predicate);
return RelMdUtil.guessSelectivity(predicate);
}
private Double getScanSelectivity(RelNode rel, RelMetadataQuery mq, RexNode predicate) {
double ROWCOUNT_UNKNOWN = -1.0;
GroupScan scan = null;
PlannerSettings settings = PrelUtil.getPlannerSettings(rel.getCluster().getPlanner());
if (rel instanceof DrillScanRel) {
scan = ((DrillScanRel) rel).getGroupScan();
} else if (rel instanceof ScanPrel) {
scan = ((ScanPrel) rel).getGroupScan();
}
if (scan != null) {
if (settings.isStatisticsEnabled()
&& scan instanceof DbGroupScan) {
double filterRows = ((DbGroupScan) scan).getRowCount(predicate, rel);
double totalRows = ((DbGroupScan) scan).getRowCount(null, rel);
if (filterRows != ROWCOUNT_UNKNOWN &&
totalRows != ROWCOUNT_UNKNOWN && totalRows > 0) {
return Math.min(1.0, filterRows / totalRows);
}
}
}
// Do not mess with statistics used for DBGroupScans.
if (rel instanceof TableScan) {
if (DrillRelOptUtil.guessRows(rel)) {
return super.getSelectivity(rel, mq, predicate);
}
DrillTable table = rel.getTable().unwrap(DrillTable.class);
if (table == null) {
table = rel.getTable().unwrap(DrillTranslatableTable.class).getDrillTable();
}
if (table != null && table.getStatsTable() != null && table.getStatsTable().isMaterialized()) {
if (rel instanceof DrillScanRelBase) {
List<String> fieldNames = new ArrayList<>();
for (SchemaPath fieldPath : ((DrillScanRelBase)rel).getGroupScan().getColumns()) {
fieldNames.add(fieldPath.toString());
}
return getScanSelectivityInternal(table, predicate, fieldNames);
} else {
return getScanSelectivityInternal(table, predicate, rel.getRowType().getFieldNames());
}
}
}
return super.getSelectivity(rel, mq, predicate);
}
private double getScanSelectivityInternal(DrillTable table, RexNode predicate, List<String> fieldNames) {
double sel = 1.0;
if ((predicate == null) || predicate.isAlwaysTrue()) {
return sel;
}
for (RexNode pred : RelOptUtil.conjunctions(predicate)) {
double orSel = 0;
for (RexNode orPred : RelOptUtil.disjunctions(pred)) {
//CALCITE guess
Double guess = RelMdUtil.guessSelectivity(pred);
if (orPred.isA(SqlKind.EQUALS)) {
if (orPred instanceof RexCall) {
int colIdx = -1;
RexInputRef op = findRexInputRef(orPred);
if (op != null) {
colIdx = op.hashCode();
}
if (colIdx != -1 && colIdx < fieldNames.size()) {
String col = fieldNames.get(colIdx);
if (table.getStatsTable() != null
&& table.getStatsTable().getNdv(col) != null) {
orSel += 1.00 / table.getStatsTable().getNdv(col);
} else {
orSel += guess;
}
} else {
orSel += guess;
if (logger.isDebugEnabled()) {
logger.warn(String.format("No input reference $[%s] found for predicate [%s]",
Integer.toString(colIdx), orPred.toString()));
}
}
}
} else {
//Use the CALCITE guess. TODO: Use histograms for COMPARISON operator
orSel += guess;
}
}
sel *= orSel;
}
// Cap selectivity if it exceeds 1.0
return (sel > 1.0) ? 1.0 : sel;
}
private Double getJoinSelectivity(DrillJoinRelBase rel, RelMetadataQuery mq, RexNode predicate) {
double sel = 1.0;
// determine which filters apply to the left vs right
RexNode leftPred, rightPred;
JoinRelType joinType = rel.getJoinType();
final RexBuilder rexBuilder = rel.getCluster().getRexBuilder();
int[] adjustments = new int[rel.getRowType().getFieldCount()];
if (DrillRelOptUtil.guessRows(rel)) {
return super.getSelectivity(rel, mq, predicate);
}
if (predicate != null) {
RexNode pred;
List<RexNode> leftFilters = new ArrayList<>();
List<RexNode> rightFilters = new ArrayList<>();
List<RexNode> joinFilters = new ArrayList<>();
List<RexNode> predList = RelOptUtil.conjunctions(predicate);
RelOptUtil.classifyFilters(
rel,
predList,
joinType,
joinType == JoinRelType.INNER,
!joinType.generatesNullsOnLeft(),
!joinType.generatesNullsOnRight(),
joinFilters,
leftFilters,
rightFilters);
leftPred =
RexUtil.composeConjunction(rexBuilder, leftFilters, true);
rightPred =
RexUtil.composeConjunction(rexBuilder, rightFilters, true);
for (RelNode child : rel.getInputs()) {
RexNode modifiedPred = null;
if (child == rel.getLeft()) {
pred = leftPred;
} else {
pred = rightPred;
}
if (pred != null) {
// convert the predicate to reference the types of the children
modifiedPred =
pred.accept(new RelOptUtil.RexInputConverter(
rexBuilder,
null,
child.getRowType().getFieldList(),
adjustments));
}
sel *= mq.getSelectivity(child, modifiedPred);
}
sel *= RelMdUtil.guessSelectivity(RexUtil.composeConjunction(rexBuilder, joinFilters, true));
}
return sel;
}
public static RexInputRef findRexInputRef(final RexNode node) {
try {
RexVisitor<Void> visitor =
new RexVisitorImpl<Void>(true) {
public Void visitCall(RexCall call) {
for (RexNode child : call.getOperands()) {
child.accept(this);
}
return super.visitCall(call);
}
public Void visitInputRef(RexInputRef inputRef) {
throw new Util.FoundOne(inputRef);
}
};
node.accept(visitor);
return null;
} catch (Util.FoundOne e) {
Util.swallow(e, null);
return (RexInputRef) e.getNode();
}
}
}
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