Here you have a more complex filter that does not simply filter out data based on directly available information. Rather, it lets you specify a dependent column—or reference column—that controls how other columns are filtered. It uses th
Here you have a more complex filter that does not simply filter out data based on directly available information. Rather, it lets you specify a dependent column—or reference column—that controls how other columns are filtered. It uses the timestamp of the reference column and includes all other columns that have the same timestamp.
尝试找到该列所在的每一行，并返回该行具有相同时间戳的全部键值对。如果某一行不包含指定的列，则该行的任何键值对都不返回。
如果dropDependentColumn=true，则从属列不返回。
via: http://abloz.com/2012/08/22/the-hbases-content-query-2.html
package com.fatkun.filter.comparison;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.BinaryPrefixComparator;
import org.apache.hadoop.hbase.filter.CompareFilter;
import org.apache.hadoop.hbase.filter.DependentColumnFilter;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.SubstringComparator;
import org.apache.hadoop.hbase.filter.ValueFilter;
import org.apache.hadoop.hbase.filter.WritableByteArrayComparable;
import org.apache.hadoop.hbase.util.Bytes;
public class TestHbaseDependentColumnFilter {
String tableName = "test_value_filter";
Configuration config = HBaseConfiguration.create();
public void filter(boolean drop, CompareFilter.CompareOp operator,
WritableByteArrayComparable comparator) throws IOException {
HTable table = new HTable(config, tableName);
//
Filter filter;
if (comparator != null) {
// drop为true时，filter表示对"col1"列以外的所有"data1"列族数据做filter操作
// drop为false时,表示对所有"data1"列族的数据做filter操作
filter = new DependentColumnFilter(Bytes.toBytes("data1"),
Bytes.toBytes("col1"), drop, operator, comparator);
} else {
filter = new DependentColumnFilter(Bytes.toBytes("data1"),
Bytes.toBytes("col1"), drop);
}
// filter应用于scan
Scan scan = new Scan();
scan.setFilter(filter);
ResultScanner scanner = table.getScanner(scan);
for (Result result : scanner) {
for (KeyValue kv : result.list()) {
System.out.println("kv=" + kv.toString() + ",value="
+ Bytes.toString(kv.getValue()));
}
}
scanner.close();
table.close();
}
/**
* 部分代码来自hbase权威指南
*
* @throws IOException
*/
public void testFilter() throws IOException {
// The dropDependentColumn parameter is giving you additional control
// over how the reference column is handled: it is either included or
// dropped by the filter
// 1.获取整个"data1"列族当前Version中的所有timestamp等于参照列"data1:col1"的数据
System.out.println("drop=false");
filter(false, CompareFilter.CompareOp.NO_OP, null);
// 2.获取除了"col1"列以外的"data1"列族中的所有timestamp等于参照列"data1:col1"的数据
System.out.println("drop=true");
filter(true, CompareFilter.CompareOp.NO_OP, null);
// 3.获取除了"col1"列以外的"data1"列族当前Version中的所有timestamp等于参照列"data1:col1"的,value以"data100"开头的所有数据
System.out.println("比较");
filter(true, CompareFilter.CompareOp.EQUAL, new BinaryPrefixComparator(
Bytes.toBytes("data100")));
}
/**
* 初始化数据
*/
public void init() {
// 创建表和初始化数据
try {
HBaseAdmin admin = new HBaseAdmin(config);
if (!admin.tableExists(tableName)) {
HTableDescriptor htd = new HTableDescriptor(tableName);
HColumnDescriptor hcd1 = new HColumnDescriptor("data1");
htd.addFamily(hcd1);
HColumnDescriptor hcd2 = new HColumnDescriptor("data2");
htd.addFamily(hcd2);
HColumnDescriptor hcd3 = new HColumnDescriptor("data3");
htd.addFamily(hcd3);
admin.createTable(htd);
}
HTable table = new HTable(config, tableName);
table.setAutoFlush(false);
int count = 50;
for (int i = 1; i <= count; ++i) {
Put p = new Put(String.format("row%03d", i).getBytes());
p.add("data1".getBytes(), String.format("col%01d", i % 10)
.getBytes(), String.format("data1%03d", i).getBytes());
p.add("data2".getBytes(), String.format("col%01d", i % 10)
.getBytes(), String.format("data2%03d", i).getBytes());
p.add("data3".getBytes(), String.format("col%01d", i % 10)
.getBytes(), String.format("data3%03d", i).getBytes());
table.put(p);
}
table.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
TestHbaseDependentColumnFilter test = new TestHbaseDependentColumnFilter();
test.init();
test.testFilter();
}
}原文地址：Hbase DependentColumnFilter, 感谢原作者分享。
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