Java tutorial
/** * 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.logical; import java.io.IOException; import java.util.List; import org.apache.drill.common.JSONOptions; import org.apache.drill.common.exceptions.DrillRuntimeException; import org.apache.drill.common.expression.SchemaPath; import org.apache.drill.common.logical.data.LogicalOperator; import org.apache.drill.common.logical.data.Scan; import org.apache.drill.exec.physical.base.GroupScan; import org.apache.drill.exec.physical.base.ScanStats; import org.apache.drill.exec.planner.common.DrillScanRelBase; import org.apache.drill.exec.planner.cost.DrillCostBase.DrillCostFactory; import org.apache.drill.exec.planner.physical.PlannerSettings; import org.apache.drill.exec.planner.physical.PrelUtil; import org.apache.drill.exec.planner.torel.ConversionContext; import org.apache.calcite.rel.RelWriter; import org.apache.calcite.plan.RelOptCluster; import org.apache.calcite.plan.RelOptCost; import org.apache.calcite.plan.RelOptPlanner; import org.apache.calcite.plan.RelOptTable; import org.apache.calcite.plan.RelTraitSet; import org.apache.calcite.rel.type.RelDataType; import com.google.common.base.Preconditions; import com.google.common.base.Predicate; import com.google.common.collect.Iterables; /** * GroupScan of a Drill table. */ public class DrillScanRel extends DrillScanRelBase implements DrillRel { private final static int STAR_COLUMN_COST = 10000; final private RelDataType rowType; private GroupScan groupScan; private List<SchemaPath> columns; private PlannerSettings settings; /** Creates a DrillScan. */ public DrillScanRel(final RelOptCluster cluster, final RelTraitSet traits, final RelOptTable table) { // By default, scan does not support project pushdown. // Decision whether push projects into scan will be made solely in DrillPushProjIntoScanRule. this(cluster, traits, table, table.getRowType(), GroupScan.ALL_COLUMNS); this.settings = PrelUtil.getPlannerSettings(cluster.getPlanner()); } /** Creates a DrillScan. */ public DrillScanRel(final RelOptCluster cluster, final RelTraitSet traits, final RelOptTable table, final RelDataType rowType, final List<SchemaPath> columns) { super(DRILL_LOGICAL, cluster, traits, table); this.settings = PrelUtil.getPlannerSettings(cluster.getPlanner()); this.rowType = rowType; if (columns == null) { // planner asks to scan all of the columns this.columns = ColumnList.all(); } else if (columns.size() == 0) { // planner asks to skip all of the columns this.columns = ColumnList.none(); } else { // planner asks to scan some columns this.columns = ColumnList.some(columns); } try { this.groupScan = drillTable.getGroupScan().clone(this.columns); } catch (final IOException e) { throw new DrillRuntimeException("Failure creating scan.", e); } } /** Creates a DrillScanRel for a particular GroupScan */ public DrillScanRel(final RelOptCluster cluster, final RelTraitSet traits, final RelOptTable table, final GroupScan groupScan, final RelDataType rowType, final List<SchemaPath> columns) { super(DRILL_LOGICAL, cluster, traits, table); this.rowType = rowType; this.columns = columns; this.groupScan = groupScan; this.settings = PrelUtil.getPlannerSettings(cluster.getPlanner()); } // // private static GroupScan getCopy(GroupScan scan){ // try { // return (GroupScan) scan.getNewWithChildren((List<PhysicalOperator>) (Object) Collections.emptyList()); // } catch (ExecutionSetupException e) { // throw new DrillRuntimeException("Unexpected failure while coping node.", e); // } // } public List<SchemaPath> getColumns() { return this.columns; } @Override public LogicalOperator implement(DrillImplementor implementor) { Scan.Builder builder = Scan.builder(); builder.storageEngine(drillTable.getStorageEngineName()); builder.selection(new JSONOptions(drillTable.getSelection())); implementor.registerSource(drillTable); return builder.build(); } public static DrillScanRel convert(Scan scan, ConversionContext context) { return new DrillScanRel(context.getCluster(), context.getLogicalTraits(), context.getTable(scan)); } @Override public RelDataType deriveRowType() { return this.rowType; } @Override public RelWriter explainTerms(RelWriter pw) { return super.explainTerms(pw).item("groupscan", groupScan.getDigest()); } @Override public double getRows() { return this.groupScan.getScanStats(settings).getRecordCount(); } /// TODO: this method is same as the one for ScanPrel...eventually we should consolidate /// this and few other methods in a common base class which would be extended /// by both logical and physical rels. @Override public RelOptCost computeSelfCost(final RelOptPlanner planner) { final ScanStats stats = groupScan.getScanStats(settings); int columnCount = getRowType().getFieldCount(); double ioCost = 0; boolean isStarQuery = Iterables.tryFind(getRowType().getFieldNames(), new Predicate<String>() { @Override public boolean apply(String input) { return Preconditions.checkNotNull(input).equals("*"); } }).isPresent(); if (isStarQuery) { columnCount = STAR_COLUMN_COST; } // double rowCount = RelMetadataQuery.getRowCount(this); double rowCount = stats.getRecordCount(); if (rowCount < 1) { rowCount = 1; } if (PrelUtil.getSettings(getCluster()).useDefaultCosting()) { return planner.getCostFactory().makeCost(rowCount * columnCount, stats.getCpuCost(), stats.getDiskCost()); } double cpuCost = rowCount * columnCount; // for now, assume cpu cost is proportional to row count. // Even though scan is reading from disk, in the currently generated plans all plans will // need to read the same amount of data, so keeping the disk io cost 0 is ok for now. // In the future we might consider alternative scans that go against projections or // different compression schemes etc that affect the amount of data read. Such alternatives // would affect both cpu and io cost. DrillCostFactory costFactory = (DrillCostFactory) planner.getCostFactory(); return costFactory.makeCost(rowCount, cpuCost, ioCost, 0); } public GroupScan getGroupScan() { return groupScan; } }