| /* |
| * 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 org.apache.drill.shaded.guava.com.google.common.collect.ImmutableList; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| import org.apache.calcite.plan.RelOptRule; |
| import org.apache.calcite.plan.RelOptRuleCall; |
| import org.apache.calcite.plan.RelOptRuleOperand; |
| import org.apache.calcite.rel.RelNode; |
| import org.apache.drill.exec.physical.base.GroupScan; |
| import org.apache.drill.exec.planner.common.DrillRelOptUtil; |
| |
| public abstract class DrillPushLimitToScanRule extends RelOptRule { |
| private static final Logger logger = LoggerFactory.getLogger(DrillPushLimitToScanRule.class); |
| |
| private DrillPushLimitToScanRule(RelOptRuleOperand operand, String description) { |
| super(operand, DrillRelFactories.LOGICAL_BUILDER, description); |
| } |
| |
| public static DrillPushLimitToScanRule LIMIT_ON_SCAN = |
| new DrillPushLimitToScanRule(RelOptHelper.some(DrillLimitRel.class, RelOptHelper.any(DrillScanRel.class)), |
| "DrillPushLimitToScanRule_LimitOnScan") { |
| @Override |
| public boolean matches(RelOptRuleCall call) { |
| DrillLimitRel limitRel = call.rel(0); |
| DrillScanRel scanRel = call.rel(1); |
| // For now only applies to Parquet. And pushdown only applies to LIMIT but not OFFSET, |
| // so if getFetch() return null no need to run this rule. |
| if (scanRel.getGroupScan().supportsLimitPushdown() && (limitRel.getFetch() != null)) { |
| return true; |
| } |
| return false; |
| } |
| |
| @Override |
| public void onMatch(RelOptRuleCall call) { |
| DrillLimitRel limitRel = call.rel(0); |
| DrillScanRel scanRel = call.rel(1); |
| doOnMatch(call, limitRel, scanRel, null); |
| } |
| }; |
| |
| public static DrillPushLimitToScanRule LIMIT_ON_PROJECT = new DrillPushLimitToScanRule( |
| RelOptHelper.some(DrillLimitRel.class, RelOptHelper.any(DrillProjectRel.class)), "DrillPushLimitToScanRule_LimitOnProject") { |
| @Override |
| public boolean matches(RelOptRuleCall call) { |
| DrillLimitRel limitRel = call.rel(0); |
| DrillProjectRel projectRel = call.rel(1); |
| // pushdown only apply limit but not offset, |
| // so if getFetch() return null no need to run this rule. |
| // Do not push across Project containing CONVERT_FROMJSON for limit 0 queries. For limit 0 queries, this would |
| // mess up the schema since Convert_FromJson() is different from other regular functions in that it only knows |
| // the output schema after evaluation is performed. When input has 0 row, Drill essentially does not have a way |
| // to know the output type. |
| // Cannot pushdown limit and offset in to flatten as long as we don't know data distribution in flattened field |
| if (!limitRel.isPushDown() && (limitRel.getFetch() != null) |
| && (!DrillRelOptUtil.isLimit0(limitRel.getFetch()) |
| || !DrillRelOptUtil.isProjectOutputSchemaUnknown(projectRel)) |
| && !DrillRelOptUtil.isProjectOutputRowcountUnknown(projectRel)) { |
| return true; |
| } |
| return false; |
| } |
| |
| @Override |
| public void onMatch(RelOptRuleCall call) { |
| DrillLimitRel limitRel = call.rel(0); |
| DrillProjectRel projectRel = call.rel(1); |
| RelNode child = projectRel.getInput(); |
| final RelNode limitUnderProject = limitRel.copy(limitRel.getTraitSet(), ImmutableList.of(child)); |
| final RelNode newProject = projectRel.copy(projectRel.getTraitSet(), ImmutableList.of(limitUnderProject)); |
| call.transformTo(newProject); |
| } |
| }; |
| |
| protected void doOnMatch(RelOptRuleCall call, DrillLimitRel limitRel, |
| DrillScanRel scanRel, DrillProjectRel projectRel) { |
| try { |
| final int rowCountRequested = (int) limitRel.estimateRowCount(limitRel.getCluster().getMetadataQuery()); |
| |
| final GroupScan newGroupScan = scanRel.getGroupScan().applyLimit(rowCountRequested); |
| |
| if (newGroupScan == null ) { |
| return; |
| } |
| |
| DrillScanRel newScanRel = new DrillScanRel(scanRel.getCluster(), |
| scanRel.getTraitSet(), |
| scanRel.getTable(), |
| newGroupScan, |
| scanRel.getRowType(), |
| scanRel.getColumns(), |
| scanRel.partitionFilterPushdown()); |
| |
| final RelNode newLimit; |
| if (projectRel != null) { |
| final RelNode newProject = projectRel.copy(projectRel.getTraitSet(), ImmutableList.of(newScanRel)); |
| newLimit = limitRel.copy(limitRel.getTraitSet(), ImmutableList.of(newProject)); |
| } else { |
| newLimit = limitRel.copy(limitRel.getTraitSet(), ImmutableList.of(newScanRel)); |
| } |
| |
| call.transformTo(newLimit); |
| logger.debug("Converted to a new DrillScanRel" + newScanRel.getGroupScan()); |
| } catch (Exception e) { |
| logger.warn("Exception while using the pruned partitions.", e); |
| } |
| } |
| } |