org.apache.hadoop.hive.ql.metadata.HiveStoragePredicateHandler Maven / Gradle / Ivy
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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.hadoop.hive.ql.metadata;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeGenericFuncDesc;
import org.apache.hadoop.hive.serde2.Deserializer;
import org.apache.hadoop.mapred.JobConf;
import java.io.Serializable;
/**
* HiveStoragePredicateHandler is an optional companion to {@link
* HiveStorageHandler}; it should only be implemented by handlers which
* support decomposition of predicates being pushed down into table scans.
*/
public interface HiveStoragePredicateHandler {
/**
* Gives the storage handler a chance to decompose a predicate. The storage
* handler should analyze the predicate and return the portion of it which
* cannot be evaluated during table access. For example, if the original
* predicate is x = 2 AND upper(y)='YUM', the storage handler
* might be able to handle x = 2 but leave the "residual"
* upper(y)='YUM' for Hive to deal with. The breakdown
* need not be non-overlapping; for example, given the
* predicate x LIKE 'a%b', the storage handler might
* be able to evaluate the prefix search x LIKE 'a%', leaving
* x LIKE '%b' as the residual.
*
* @param jobConf contains a job configuration matching the one that
* will later be passed to getRecordReader and getSplits
*
* @param deserializer deserializer which will be used when
* fetching rows
*
* @param predicate predicate to be decomposed
*
* @return decomposed form of predicate, or null if no pushdown is
* possible at all
*/
public DecomposedPredicate decomposePredicate(
JobConf jobConf,
Deserializer deserializer,
ExprNodeDesc predicate);
/**
* Struct class for returning multiple values from decomposePredicate.
*/
public static class DecomposedPredicate {
/**
* Portion of predicate to be evaluated by storage handler. Hive
* will pass this into the storage handler's input format.
*/
public ExprNodeGenericFuncDesc pushedPredicate;
/**
* Serialized format for filter
*/
public Serializable pushedPredicateObject;
/**
* Portion of predicate to be post-evaluated by Hive for any rows
* which are returned by storage handler.
*/
public ExprNodeGenericFuncDesc residualPredicate;
}
}