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

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Here is the source code for org.apache.drill.optiq.DrillSortRel.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 java.util.List;

import net.hydromatic.linq4j.Ord;

import org.eigenbase.rel.RelCollation;
import org.eigenbase.rel.RelFieldCollation;
import org.eigenbase.rel.RelNode;
import org.eigenbase.rel.SortRel;
import org.eigenbase.relopt.RelOptCluster;
import org.eigenbase.relopt.RelTraitSet;

import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.eigenbase.rex.RexLiteral;
import org.eigenbase.rex.RexNode;

/**
 * Sort implemented in Drill.
 */
public class DrillSortRel extends SortRel implements DrillRel {

    /** Creates a DrillSortRel. */
    public DrillSortRel(RelOptCluster cluster, RelTraitSet traits, RelNode input, RelCollation collation) {
        super(cluster, traits, input, collation);
    }

    /** Creates a DrillSortRel with offset and fetch. */
    public DrillSortRel(RelOptCluster cluster, RelTraitSet traits, RelNode input, RelCollation collation,
            RexNode offset, RexNode fetch) {
        super(cluster, traits, input, collation, offset, fetch);
    }

    @Override
    public DrillSortRel copy(RelTraitSet traitSet, RelNode input, RelCollation collation, RexNode offset,
            RexNode fetch) {
        return new DrillSortRel(getCluster(), traitSet, input, collation, offset, fetch);
    }

    @Override
    public int implement(DrillImplementor implementor) {
        int inputId = implementor.visitChild(this, 0, getChild());
        final List<String> childFields = getChild().getRowType().getFieldNames();
        /*
         * E.g. { op: "order", input: 4, ordering: [ {order: "asc", expr: "deptId"} ] }
         */
        final ObjectNode order = implementor.mapper.createObjectNode();
        order.put("op", "order");
        order.put("input", inputId);
        final ArrayNode orderings = implementor.mapper.createArrayNode();
        order.put("orderings", orderings);
        for (Ord<RelFieldCollation> fieldCollation : Ord.zip(this.collation.getFieldCollations())) {
            final ObjectNode ordering = implementor.mapper.createObjectNode();
            ordering.put("order", toDrill(fieldCollation.e));
            ordering.put("expr", childFields.get(fieldCollation.e.getFieldIndex()));
            switch (fieldCollation.e.nullDirection) {
            case FIRST:
                ordering.put("nullCollation", "first");
                break;
            default:
                ordering.put("nullCollation", "last");
                break;
            }
            orderings.add(ordering);
        }

        return implementor.add(order);
    }

    private static String toDrill(RelFieldCollation collation) {
        switch (collation.getDirection()) {
        case Ascending:
            return "asc";
        case Descending:
            return "desc";
        default:
            throw new AssertionError(collation.getDirection());
        }
    }
}