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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.exec.planner;
import java.util.Iterator;
import java.util.List;
import org.apache.calcite.rel.core.TableScan;
import org.apache.drill.exec.store.dfs.MetadataContext;
import org.apache.hadoop.fs.Path;
/**
* Abstract base class for file system based partition descriptors and Hive partition descriptors.
*
*/
public abstract class AbstractPartitionDescriptor implements PartitionDescriptor, Iterable<List<PartitionLocation>> {
/**
* A sequence of sublists of partition locations combined into a single super list.
* The size of each sublist is at most {@link PartitionDescriptor#PARTITION_BATCH_SIZE}
* For example if the size is 3, the complete list could be: {(a, b, c), {d, e, f), (g, h)}
*/
protected List<List<PartitionLocation>> locationSuperList;
/**
* Flag to indicate if the sublists of the partition locations has been created
*/
protected boolean sublistsCreated = false;
/**
* Create sublists of the partition locations, each sublist of size
* at most {@link PartitionDescriptor#PARTITION_BATCH_SIZE}
*/
protected abstract void createPartitionSublists();
/**
* Iterator that traverses over the super list of partition locations and
* each time returns a single sublist of partition locations.
*/
@Override
public Iterator<List<PartitionLocation>> iterator() {
if (!sublistsCreated) {
createPartitionSublists();
}
return locationSuperList.iterator();
}
@Override
public boolean supportsMetadataCachePruning() {
return false;
}
@Override
public TableScan createTableScan(List<PartitionLocation> newPartitions, Path cacheFileRoot,
boolean isAllPruned, MetadataContext metaContext) throws Exception {
throw new UnsupportedOperationException();
}
}
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