/**
* 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.hadoop.hive.hbase;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.index.IndexPredicateAnalyzer;
import org.apache.hadoop.hive.ql.index.IndexSearchCondition;
import org.apache.hadoop.hive.ql.metadata.HiveStoragePredicateHandler.DecomposedPredicate;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeGenericFuncDesc;
/**
* Simple abstract class to help with creation of a {@link DecomposedPredicate}. In order to create
* one, consumers should extend this class and override the "getScanRange" method to define the
* start/stop keys and/or filters on their hbase scans
* */
public abstract class AbstractHBaseKeyPredicateDecomposer {
public static final Log LOG = LogFactory.getLog(AbstractHBaseKeyPredicateDecomposer.class);
public DecomposedPredicate decomposePredicate(String keyColName, ExprNodeDesc predicate) {
IndexPredicateAnalyzer analyzer = IndexPredicateAnalyzer.createAnalyzer(true);
analyzer.allowColumnName(keyColName);
analyzer.setAcceptsFields(true);
analyzer.setFieldValidator(getFieldValidator());
DecomposedPredicate decomposed = new DecomposedPredicate();
List<IndexSearchCondition> conditions = new ArrayList<IndexSearchCondition>();
decomposed.residualPredicate =
(ExprNodeGenericFuncDesc) analyzer.analyzePredicate(predicate, conditions);
if (!conditions.isEmpty()) {
decomposed.pushedPredicate = analyzer.translateSearchConditions(conditions);
try {
decomposed.pushedPredicateObject = getScanRange(conditions);
} catch (Exception e) {
LOG.warn("Failed to decompose predicates", e);
return null;
}
}
return decomposed;
}
/**
* Get the scan range that specifies the start/stop keys and/or filters to be applied onto the
* hbase scan
* */
protected abstract HBaseScanRange getScanRange(List<IndexSearchCondition> searchConditions)
throws Exception;
/**
* Get an optional {@link IndexPredicateAnalyzer.FieldValidator validator}. A validator can be
* used to optinally filter out the predicates which need not be decomposed. By default this
* method returns {@code null} which means that all predicates are pushed but consumers can choose
* to override this to provide a custom validator as well.
* */
protected IndexPredicateAnalyzer.FieldValidator getFieldValidator() {
return null;
}
}