blob: 28489156e2d433622f341d477bfea89bbb45d8a2 [file] [log] [blame]
/*
* 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 org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.util.Bytes;
import java.io.DataOutput;
import java.io.IOException;
import java.io.DataInput;
/**
* This filter is used for selecting only those keys with columns that matches
* a particular prefix. For example, if prefix is 'an', it will pass keys will
* columns like 'and', 'anti' but not keys with columns like 'ball', 'act'.
*/
public class ColumnPrefixFilter extends FilterBase {
protected byte [] prefix = null;
public ColumnPrefixFilter() {
super();
}
public ColumnPrefixFilter(final byte [] prefix) {
this.prefix = prefix;
}
public byte[] getPrefix() {
return prefix;
}
@Override
public ReturnCode filterKeyValue(KeyValue kv) {
if (this.prefix == null || kv.getBuffer() == null) {
return ReturnCode.INCLUDE;
} else {
return filterColumn(kv.getBuffer(), kv.getQualifierOffset(), kv.getQualifierLength());
}
}
public ReturnCode filterColumn(byte[] buffer, int qualifierOffset, int qualifierLength) {
if (qualifierLength < prefix.length) {
int cmp = Bytes.compareTo(buffer, qualifierOffset, qualifierLength, this.prefix, 0,
qualifierLength);
if (cmp <= 0) {
return ReturnCode.SEEK_NEXT_USING_HINT;
} else {
return ReturnCode.NEXT_ROW;
}
} else {
int cmp = Bytes.compareTo(buffer, qualifierOffset, this.prefix.length, this.prefix, 0,
this.prefix.length);
if (cmp < 0) {
return ReturnCode.SEEK_NEXT_USING_HINT;
} else if (cmp > 0) {
return ReturnCode.NEXT_ROW;
} else {
return ReturnCode.INCLUDE;
}
}
}
public void write(DataOutput out) throws IOException {
Bytes.writeByteArray(out, this.prefix);
}
public void readFields(DataInput in) throws IOException {
this.prefix = Bytes.readByteArray(in);
}
public KeyValue getNextKeyHint(KeyValue kv) {
return KeyValue.createFirstOnRow(
kv.getBuffer(), kv.getRowOffset(), kv.getRowLength(), kv.getBuffer(),
kv.getFamilyOffset(), kv.getFamilyLength(), prefix, 0, prefix.length);
}
}