/*
* Copyright 2010 The Apache Software Foundation
*
* 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.hbase.filter;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.util.Bytes;
import java.util.ArrayList;
import com.google.common.base.Preconditions;
/**
* A filter that will only return the key component of each KV (the value will
* be rewritten as empty).
* <p>
* This filter can be used to grab all of the keys without having to also grab
* the values.
*/
public class KeyOnlyFilter extends FilterBase {
boolean lenAsVal;
public KeyOnlyFilter() { this(false); }
public KeyOnlyFilter(boolean lenAsVal) { this.lenAsVal = lenAsVal; }
@Override
public KeyValue transform(KeyValue kv) {
return kv.createKeyOnly(this.lenAsVal);
}
public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
Preconditions.checkArgument(filterArguments.size() == 0,
"Expected: 0 but got: %s", filterArguments.size());
return new KeyOnlyFilter();
}
public void write(DataOutput out) throws IOException {
out.writeBoolean(this.lenAsVal);
}
public void readFields(DataInput in) throws IOException {
this.lenAsVal = in.readBoolean();
}
}