/**
* 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.physical;
import java.io.IOException;
import java.util.List;
import net.hydromatic.linq4j.Ord;
import org.apache.drill.exec.physical.base.PhysicalOperator;
import org.apache.drill.exec.physical.config.HashToRandomExchange;
import org.apache.drill.exec.physical.config.SelectionVectorRemover;
import org.apache.drill.exec.planner.cost.DrillCostBase;
import org.apache.drill.exec.planner.cost.DrillCostBase.DrillCostFactory;
import org.apache.drill.exec.planner.physical.DrillDistributionTrait.DistributionField;
import org.apache.drill.exec.record.BatchSchema.SelectionVectorMode;
import org.eigenbase.rel.RelNode;
import org.eigenbase.rel.RelWriter;
import org.eigenbase.rel.SingleRel;
import org.eigenbase.rel.metadata.RelMetadataQuery;
import org.eigenbase.relopt.RelOptCluster;
import org.eigenbase.relopt.RelOptCost;
import org.eigenbase.relopt.RelOptPlanner;
import org.eigenbase.relopt.RelTraitSet;
import org.eigenbase.reltype.RelDataTypeField;
import org.eigenbase.rex.RexNode;
public class HashToRandomExchangePrel extends ExchangePrel {
private final List<DistributionField> fields;
public HashToRandomExchangePrel(RelOptCluster cluster, RelTraitSet traitSet, RelNode input, List<DistributionField> fields) {
super(cluster, traitSet, input);
this.fields = fields;
assert input.getConvention() == Prel.DRILL_PHYSICAL;
}
/**
* HashToRandomExchange processes M input rows and hash partitions them
* based on computing a hash value on the distribution fields.
* If there are N nodes (endpoints), we can assume for costing purposes
* on average each sender will send M/N rows to 1 destination endpoint.
* (See DrillCostBase for symbol notations)
* Include impact of skewness of distribution : the more keys used, the less likely the distribution will be skewed.
* The hash cpu cost will be proportional to 1 / #_keys.
* C = CPU cost of hashing k fields of M/N rows
* + CPU cost of SV remover for M/N rows
* + Network cost of sending M/N rows to 1 destination.
* So, C = (h * 1/k * M/N) + (s * M/N) + (w * M/N)
* Total cost = N * C
*/
@Override
public RelOptCost computeSelfCost(RelOptPlanner planner) {
if (PrelUtil.getSettings(getCluster()).useDefaultCosting()) {
return super.computeSelfCost(planner).multiplyBy(.1);
}
RelNode child = this.getChild();
double inputRows = RelMetadataQuery.getRowCount(child);
int rowWidth = child.getRowType().getFieldCount() * DrillCostBase.AVG_FIELD_WIDTH;
double hashCpuCost = DrillCostBase.HASH_CPU_COST * inputRows / fields.size();
double svrCpuCost = DrillCostBase.SVR_CPU_COST * inputRows;
double networkCost = DrillCostBase.BYTE_NETWORK_COST * inputRows * rowWidth;
DrillCostFactory costFactory = (DrillCostFactory)planner.getCostFactory();
return costFactory.makeCost(inputRows, hashCpuCost + svrCpuCost, 0, networkCost);
}
@Override
public RelNode copy(RelTraitSet traitSet, List<RelNode> inputs) {
return new HashToRandomExchangePrel(getCluster(), traitSet, sole(inputs), fields);
}
public PhysicalOperator getPhysicalOperator(PhysicalPlanCreator creator) throws IOException {
Prel child = (Prel) this.getChild();
PhysicalOperator childPOP = child.getPhysicalOperator(creator);
if(PrelUtil.getSettings(getCluster()).isSingleMode()) return childPOP;
HashToRandomExchange g = new HashToRandomExchange(childPOP, PrelUtil.getHashExpression(this.fields, getChild().getRowType()));
return creator.addMetadata(this, g);
}
public List<DistributionField> getFields() {
return this.fields;
}
@Override
public RelWriter explainTerms(RelWriter pw) {
super.explainTerms(pw);
for (Ord<DistributionField> ord : Ord.zip(fields)) {
pw.item("dist" + ord.i, ord.e);
}
return pw;
}
@Override
public SelectionVectorMode getEncoding() {
return SelectionVectorMode.NONE;
}
@Override
public SelectionVectorMode[] getSupportedEncodings() {
return SelectionVectorMode.ALL;
}
}