org.apache.calcite.adapter.pig.PigToEnumerableConverter Maven / Gradle / Ivy
/*
* 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.calcite.adapter.pig;
import org.apache.calcite.adapter.enumerable.EnumerableRel;
import org.apache.calcite.adapter.enumerable.EnumerableRelImplementor;
import org.apache.calcite.adapter.enumerable.JavaRowFormat;
import org.apache.calcite.adapter.enumerable.PhysType;
import org.apache.calcite.adapter.enumerable.PhysTypeImpl;
import org.apache.calcite.linq4j.tree.BlockBuilder;
import org.apache.calcite.linq4j.tree.Expressions;
import org.apache.calcite.plan.ConventionTraitDef;
import org.apache.calcite.plan.RelOptCluster;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.convert.ConverterImpl;
import org.apache.calcite.runtime.Hook;
import org.apache.calcite.util.BuiltInMethod;
import java.util.List;
/**
* Relational expression representing a scan of a table in a Pig data source.
*/
public class PigToEnumerableConverter
extends ConverterImpl
implements EnumerableRel {
/** Creates a PigToEnumerableConverter. */
protected PigToEnumerableConverter(
RelOptCluster cluster,
RelTraitSet traits,
RelNode input) {
super(cluster, ConventionTraitDef.INSTANCE, traits, input);
}
@Override public RelNode copy(RelTraitSet traitSet, List inputs) {
return new PigToEnumerableConverter(
getCluster(), traitSet, sole(inputs));
}
/**
* {@inheritDoc}
*
* This implementation does not actually execute the associated Pig Latin
* script and return results. Instead it returns an empty
* {@link org.apache.calcite.adapter.enumerable.EnumerableRel.Result}
* in order to allow for testing and verification of every step of query
* processing up to actual physical execution and result verification.
*
*
Next step is to invoke Pig from here, likely in local mode, have it
* store results in a predefined file so they can be read here and returned as
* a {@code Result} object.
*/
@Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
final BlockBuilder list = new BlockBuilder();
final PhysType physType =
PhysTypeImpl.of(implementor.getTypeFactory(), rowType,
pref.prefer(JavaRowFormat.ARRAY));
PigRel.Implementor impl = new PigRel.Implementor();
impl.visitChild(0, getInput());
Hook.QUERY_PLAN.run(impl.getScript()); // for script validation in tests
list.add(
Expressions.return_(null,
Expressions.call(
BuiltInMethod.EMPTY_ENUMERABLE.method)));
return implementor.result(physType, list.toBlock());
}
}