org.apache.drill.optiq.DrillProjectRel.java Source code

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Here is the source code for org.apache.drill.optiq.DrillProjectRel.java

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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.optiq;

import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

import org.eigenbase.rel.*;
import org.eigenbase.relopt.*;
import org.eigenbase.reltype.RelDataType;
import org.eigenbase.rex.RexNode;
import org.eigenbase.util.Pair;

import java.util.*;

/**
 * Project implemented in Drill.
 */
public class DrillProjectRel extends ProjectRelBase implements DrillRel {
    protected DrillProjectRel(RelOptCluster cluster, RelTraitSet traits, RelNode child, List<RexNode> exps,
            RelDataType rowType) {
        super(cluster, traits, child, exps, rowType, Flags.Boxed, Collections.<RelCollation>emptyList());
        assert getConvention() == CONVENTION;
    }

    public DrillProjectRel(RelOptCluster cluster, RelTraitSet traits, RelNode child, List<RexNode> exps,
            RelDataType rowType, int flags, List<RelCollation> collationList) {
        super(cluster, traits, child, exps, rowType, flags, collationList);

    }

    @Override
    public RelNode copy(RelTraitSet traitSet, List<RelNode> inputs) {
        return new DrillProjectRel(getCluster(), traitSet, sole(inputs), new ArrayList<RexNode>(exps), rowType);
    }

    @Override
    public RelOptCost computeSelfCost(RelOptPlanner planner) {
        return super.computeSelfCost(planner).multiplyBy(0.1);
    }

    private List<Pair<RexNode, String>> projects() {
        return Pair.zip(exps, getRowType().getFieldNames());
    }

    @Override
    public int implement(DrillImplementor implementor) {
        int inputId = implementor.visitChild(this, 0, getChild());
        final ObjectNode project = implementor.mapper.createObjectNode();
        /*
         * E.g. { op: "project", projections: [ { ref: "output.quantity", expr: "donuts.sales"} ]
         */
        project.put("op", "project");
        project.put("input", inputId);
        final ArrayNode transforms = implementor.mapper.createArrayNode();
        project.put("projections", transforms);
        for (Pair<RexNode, String> pair : projects()) {
            final ObjectNode objectNode = implementor.mapper.createObjectNode();
            transforms.add(objectNode);
            String expr = DrillOptiq.toDrill(getChild(), pair.left);
            objectNode.put("expr", expr);
            String ref = "output." + pair.right;
            //      String ref = pair.right;
            objectNode.put("ref", ref);
        }
        return implementor.add(project);
    }
}