hbase 二级索引具体实例

You need to enable indexing in HBase before you can create a secondary index on columns. Edit the file $HBASE_INSTALL_DIR/conf/hbase-site.xml and add the following property to it.

	<property>
		<name>hbase.regionserver.class</name>
		<value>org.apache.hadoop.hbase.ipc.IndexedRegionInterface</value>
	</property>      
	<property>         
		<name>hbase.regionserver.impl</name>         
		<value>org.apache.hadoop.hbase.regionserver.tableindexed.IndexedRegionServer</value>     
	</property>

//Adding secondary index while creating table:
	HBaseConfiguration conf = new HBaseConfiguration();     
	conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));      
	HTableDescriptor desc = new HTableDescriptor("test_table");      
	desc.addFamily(new HColumnDescriptor("columnfamily1:"));     
	desc.addFamily(new HColumnDescriptor("columnfamily2:"));      
	desc.addIndex(new IndexSpecification("column1",Bytes.toBytes("columnfamily1:column1")));     
	desc.addIndex(new IndexSpecification("column2",Bytes.toBytes("columnfamily1:column2")));
	IndexedTableAdmin admin = null;     
	admin = new IndexedTableAdmin(conf);      
	admin.createTable(desc);  
//Adding index in an existing table:      
	HBaseConfiguration conf = new HBaseConfiguration();     
	conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));      
	IndexedTableAdmin admin = null;     
	admin = new IndexedTableAdmin(conf);      
	admin.addIndex(Bytes.toBytes("test_table"), new IndexSpecification("column2",Bytes.toBytes("columnfamily1:column2")));  
//Deleting existing index from a table.
	HBaseConfiguration conf = new HBaseConfiguration();     
	conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));      
	IndexedTableAdmin admin = null;     
	admin = new IndexedTableAdmin(conf);      
	admin.removeIndex(Bytes.toBytes("test_table"), "column2");
//Reading from secondary indexed columns:
//To read from a secondary index, get a scanner for the index and scan through the data.      
	HBaseConfiguration conf = new HBaseConfiguration();     
	conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));      
	IndexedTable table = new IndexedTable(conf, Bytes.toBytes("test_table"));     
// You need to specify which columns to get     
	Scanner scanner = table.getIndexedScanner("column1",HConstants.EMPTY_START_ROW, null, null, new byte[][] {Bytes.toBytes("columnfamily1:column1"),Bytes.toBytes("columnfamily1:column2")});
	for (RowResult rowResult : scanner) {         
		String value1 = new String(rowResult.get(Bytes.toBytes("columnfamily1:column1")).getValue());
		String value2 = new String(rowResult.get(Bytes.toBytes("columnfamily1:column2")).getValue());         
		System.out.println(value1 + ", " + value2);     
	}      
	table.close();  
//To get a scanner to a subset of the rows specify a column filter.      
	ColumnValueFilter filter = new ColumnValueFilter(Bytes.toBytes("columnfamily1:column1"),CompareOp.LESS, Bytes.toBytes("value1-10"));      
	scanner = table.getIndexedScanner("column1", HConstants.EMPTY_START_ROW,null, filter, new byte[][] { Bytes.toBytes("columnfamily1:column1"),Bytes.toBytes("columnfamily1:column2"));      
	for (RowResult rowResult : scanner) {         
		String value1 = new String(             
				rowResult.get(Bytes.toBytes("columnfamily1:column1")).getValue());         
		String value2 = new String(rowResult.get(Bytes.toBytes("columnfamily1:column2")).getValue());         
		System.out.println(value1 + ", " + value2);     
	}
	
	Example Code:
	import java.io.IOException; 
	import java.util.Date;
	import org.apache.hadoop.fs.Path; 
	import org.apache.hadoop.hbase.HBaseConfiguration; 
	import org.apache.hadoop.hbase.HColumnDescriptor; 
	import org.apache.hadoop.hbase.HConstants; 
	import org.apache.hadoop.hbase.HTableDescriptor; 
	import org.apache.hadoop.hbase.client.Scanner; 
	import org.apache.hadoop.hbase.client.tableindexed.IndexSpecification; 
	import org.apache.hadoop.hbase.client.tableindexed.IndexedTable; 
	import org.apache.hadoop.hbase.client.tableindexed.IndexedTableAdmin; 
	import org.apache.hadoop.hbase.filter.ColumnValueFilter; 
	import org.apache.hadoop.hbase.filter.ColumnValueFilter.CompareOp; 
	import org.apache.hadoop.hbase.io.BatchUpdate; 
	import org.apache.hadoop.hbase.io.RowResult; 
	import org.apache.hadoop.hbase.util.Bytes
	
	public class SecondaryIndexTest {     
		public void writeToTable() throws IOException {         
			HBaseConfiguration conf = new HBaseConfiguration();         
			conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));          
			IndexedTable table = new IndexedTable(conf, Bytes.toBytes("test_table"));          
			String row = "test_row";         
			BatchUpdate update = null;          
			for (int i = 0; i < 100; i++) {             
				update = new BatchUpdate(row + i);             
				update.put("columnfamily1:column1", Bytes.toBytes("value1-" + i));             
				update.put("columnfamily1:column2", Bytes.toBytes("value2-" + i));             
				table.commit(update);         
			}          
			table.close(); 
		}
		
		public void readAllRowsFromSecondaryIndex() throws IOException {         
			 HBaseConfiguration conf = new HBaseConfiguration();         
			 conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));          
			 IndexedTable table = new IndexedTable(conf, Bytes.toBytes("test_table"));          
			 Scanner scanner = table.getIndexedScanner("column1",HConstants.EMPTY_START_ROW, null, null, new byte[][] {Bytes.toBytes("columnfamily1:column1"),Bytes.toBytes("columnfamily1:column2") });          
			 for (RowResult rowResult : scanner) {             
				 System.out.println(Bytes.toString(rowResult.get(Bytes.toBytes("columnfamily1:column1")).getValue())+ ", " + Bytes.toString(rowResult.get(Bytes.toBytes("columnfamily1:column2")).getValue()));         
			 }          
			 table.close();     
		}  
		
		public void readFilteredRowsFromSecondaryIndex() throws IOException {         
			 HBaseConfiguration conf = new HBaseConfiguration();         
			 conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));          
			 IndexedTable table = new IndexedTable(conf, Bytes.toBytes("test_table"));          
			 ColumnValueFilter filter = new ColumnValueFilter(Bytes.toBytes("columnfamily1:column1"),CompareOp.LESS, Bytes.toBytes("value1-40"));
			 Scanner scanner = table.getIndexedScanner("column1",HConstants.EMPTY_START_ROW, null, filter,new byte[][] { Bytes.toBytes("columnfamily1:column1"),Bytes.toBytes("columnfamily1:column2")});          
			 for (RowResult rowResult : scanner) {             
				 System.out.println(Bytes.toString(rowResult.get(Bytes.toBytes("columnfamily1:column1")).getValue())+ ", " + Bytes.toString(rowResult.get(Bytes.toBytes("columnfamily1:column2")).getValue()));
			 }          
			 table.close();     
		}  
		
		public void createTableWithSecondaryIndexes() throws IOException {         
			 HBaseConfiguration conf = new HBaseConfiguration();         
			 conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));          
			 HTableDescriptor desc = new HTableDescriptor("test_table");          
			 desc.addFamily(new HColumnDescriptor("columnfamily1:column1"));         
			 desc.addFamily(new HColumnDescriptor("columnfamily1:column2"));          
			 desc.addIndex(new IndexSpecification("column1",Bytes.toBytes("columnfamily1:column1")));         
			 desc.addIndex(new IndexSpecification("column2",Bytes.toBytes("columnfamily1:column2")));          
			 IndexedTableAdmin admin = null;         
			 admin = new IndexedTableAdmin(conf);          
			 if (admin.tableExists(Bytes.toBytes("test_table"))) {
				 if (admin.isTableEnabled("test_table")) {                 
					 admin.disableTable(Bytes.toBytes("test_table"));             
				 }              
				 admin.deleteTable(Bytes.toBytes("test_table"));         
			 }          
			 if (admin.tableExists(Bytes.toBytes("test_table-column1"))) {             
				 if (admin.isTableEnabled("test_table-column1")) {                 
					 admin.disableTable(Bytes.toBytes("test_table-column1"));             
				 }              
				 admin.deleteTable(Bytes.toBytes("test_table-column1"));         
			 }          
			 admin.createTable(desc);     
		}   
  
		public void addSecondaryIndexToExistingTable() throws IOException {         
			HBaseConfiguration conf = new HBaseConfiguration();         
			conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));          
			IndexedTableAdmin admin = null;         
			admin = new IndexedTableAdmin(conf);          
			admin.addIndex(Bytes.toBytes("test_table"),new IndexSpecification("column2",Bytes.toBytes("columnfamily1:column2")));     
		}      
		
		public void removeSecondaryIndexToExistingTable() throws IOException {         
			HBaseConfiguration conf = new HBaseConfiguration();         
			conf.addResource(new Path("/opt/hbase-0.19.3/conf/hbase-site.xml"));
			IndexedTableAdmin admin = null;         
			admin = new IndexedTableAdmin(conf);          
			admin.removeIndex(Bytes.toBytes("test_table"), "column2");     
		}     
		
		public static void main(String[] args) throws IOException {         
			SecondaryIndexTest test = new SecondaryIndexTest();         
			test.createTableWithSecondaryIndexes();         
			test.writeToTable();         
			test.addSecondaryIndexToExistingTable();         
			test.removeSecondaryIndexToExistingTable();         
			test.readAllRowsFromSecondaryIndex();         
			test.readFilteredRowsFromSecondaryIndex();          
			System.out.println("Done!");    
		 }
	}