HBase学习之路 (六)过滤器

过滤器(Filter)

　　基础API中的查询操作在面对大量数据的时候是非常苍白的，这里Hbase提供了高级的查询方法：Filter。Filter可以根据簇、列、版本等更多的条件来对数据进行过滤，基于Hbase本身提供的三维有序(主键有序、列有序、版本有序)，这些Filter可以高效的完成查询过滤的任务。带有Filter条件的RPC查询请求会把Filter分发到各个RegionServer，是一个服务器端(Server-side)的过滤器，这样也可以降低网络传输的压力。

　　要完成一个过滤的操作，至少需要两个参数。一个是抽象的操作符，Hbase提供了枚举类型的变量来表示这些抽象的操作符：LESS/LESS_OR_EQUAL/EQUAL/NOT_EUQAL等；另外一个就是具体的比较器(Comparator)，代表具体的比较逻辑，如果可以提高字节级的比较、字符串级的比较等。有了这两个参数，我们就可以清晰的定义筛选的条件，过滤数据。

抽象操作符(比较运算符)

LESS <

LESS_OR_EQUAL <=

EQUAL =

NOT_EQUAL <>

GREATER_OR_EQUAL >=

GREATER >

NO_OP 排除所有

比较器(指定比较机制)

BinaryComparator 按字节索引顺序比较指定字节数组，采用 Bytes.compareTo(byte[])

BinaryPrefixComparator 跟前面相同，只是比较左端的数据是否相同

NullComparator 判断给定的是否为空

BitComparator 按位比较

RegexStringComparator 提供一个正则的比较器，仅支持 EQUAL 和非 EQUAL

SubstringComparator 判断提供的子串是否出现在 value 中

HBase过滤器的分类

比较过滤器

1、行键过滤器 RowFilter

Filter rowFilter = new RowFilter(CompareOp.GREATER, new BinaryComparator("95007".getBytes()));
scan.setFilter(rowFilter);

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 1 public class HbaseFilterTest { 2  3     private static final String ZK_CONNECT_KEY = "hbase.zookeeper.quorum"; 4     private static final String ZK_CONNECT_VALUE = "hadoop1:2181,hadoop2:2181,hadoop3:2181"; 5  6     private static Connection conn = null; 7     private static Admin admin = null; 8      9     public static void main(String[] args) throws Exception {10         11         Configuration conf = HBaseConfiguration.create();12         conf.set(ZK_CONNECT_KEY, ZK_CONNECT_VALUE);13         conn = ConnectionFactory.createConnection(conf);14         admin = conn.getAdmin();15         Table table = conn.getTable(TableName.valueOf("student"));16         17         Scan scan = new Scan();18         19         Filter rowFilter = new RowFilter(CompareOp.GREATER, new BinaryComparator("95007".getBytes()));20         scan.setFilter(rowFilter);21         ResultScanner resultScanner = table.getScanner(scan);22         for(Result result : resultScanner) {23             List cells = result.listCells();24             for(Cell cell : cells) {25                 System.out.println(cell);26             }27         }28         29         30     }

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运行结果部分截图

2、列簇过滤器 FamilyFilter

Filter familyFilter = new FamilyFilter(CompareOp.EQUAL, new BinaryComparator("info".getBytes()));
scan.setFilter(familyFilter);

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3、列过滤器 QualifierFilter

Filter qualifierFilter = new QualifierFilter(CompareOp.EQUAL, new BinaryComparator("name".getBytes()));
scan.setFilter(qualifierFilter);

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4、值过滤器 ValueFilter

Filter valueFilter = new ValueFilter(CompareOp.EQUAL, new SubstringComparator("男"));
scan.setFilter(valueFilter);

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5、时间戳过滤器 TimestampsFilter

List list = new ArrayList<>();
list.add(1522469029503l);
TimestampsFilter timestampsFilter = new TimestampsFilter(list);
scan.setFilter(timestampsFilter);

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专用过滤器

1、单列值过滤器 SingleColumnValueFilter ----会返回满足条件的整行

SingleColumnValueFilter singleColumnValueFilter = new SingleColumnValueFilter(                "info".getBytes(), //列簇                "name".getBytes(), //列CompareOp.EQUAL, new SubstringComparator("刘晨"));//如果不设置为 true，则那些不包含指定 column 的行也会返回singleColumnValueFilter.setFilterIfMissing(true);
scan.setFilter(singleColumnValueFilter);

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2、单列值排除器 SingleColumnValueExcludeFilter

SingleColumnValueExcludeFilter singleColumnValueExcludeFilter = new SingleColumnValueExcludeFilter(                "info".getBytes(), "name".getBytes(), CompareOp.EQUAL, new SubstringComparator("刘晨"));
singleColumnValueExcludeFilter.setFilterIfMissing(true);scan.setFilter(singleColumnValueExcludeFilter);

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3、前缀过滤器 PrefixFilter----针对行键

PrefixFilter prefixFilter = new PrefixFilter("9501".getBytes());scan.setFilter(prefixFilter);

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4、列前缀过滤器 ColumnPrefixFilter

ColumnPrefixFilter columnPrefixFilter = new ColumnPrefixFilter("name".getBytes());scan.setFilter(columnPrefixFilter);

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 1 public class HbaseFilterTest2 { 2  3     private static final String ZK_CONNECT_KEY = "hbase.zookeeper.quorum"; 4     private static final String ZK_CONNECT_VALUE = "hadoop1:2181,hadoop2:2181,hadoop3:2181"; 5  6     private static Connection conn = null; 7     private static Admin admin = null; 8      9     public static void main(String[] args) throws Exception {10         11         Configuration conf = HBaseConfiguration.create();12         conf.set(ZK_CONNECT_KEY, ZK_CONNECT_VALUE);13         conn = ConnectionFactory.createConnection(conf);14         admin = conn.getAdmin();15         Table table = conn.getTable(TableName.valueOf("student"));16         17         Scan scan = new Scan();18         19         ColumnPrefixFilter columnPrefixFilter = new ColumnPrefixFilter("name".getBytes());20         21         scan.setFilter(columnPrefixFilter);22         ResultScanner resultScanner = table.getScanner(scan);23         for(Result result : resultScanner) {24             List cells = result.listCells();25             for(Cell cell : cells) {26                 System.out.println(Bytes.toString(cell.getRow()) + "\t" + Bytes.toString(cell.getFamily()) + "\t" + Bytes.toString(cell.getQualifier())27                 + "\t" + Bytes.toString(cell.getValue()) + "\t" + cell.getTimestamp());28             }29         }30         31         32     }33     34     35 }

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5、分页过滤器 PageFilter