Updated on 2024-08-16 GMT+08:00

HBase SQL Query Sample Code

Function Description

Phoenix is an intermediate structured query language (SQL) layer built on HBase. Phoenix provides a JDBC driver that can be embedded in a client. The Phoenix query engine converts input SQL statements to one or more HBase scans, and compiles and executes the scan tasks to generate a standard JDBC result set.

Sample Code

  • A temporary directory for storing intermediate query results is configured in hbase-example/conf/hbase-site.xml on the client. If a client program executes the temporary directory on Linux, configure a Linux path. If a client program executes the temporary directory on Windows, configure a Windows path.
    <property>
         <name>phoenix.spool.directory</name>
         <value>[1] Temporary directory for storing intermediate query results</value>
    </property>
  • Java example: Using the JDBC interface to access HBase
             public String getURL(Configuration conf) 
              {  
                 String phoenix_jdbc = "jdbc:phoenix"; 
                 String zkQuorum = conf.get("hbase.zookeeper.quorum");      
                 return phoenix_jdbc + ":" + zkQuorum; 
              } 
               
              public void testSQL() 
              { 
                 String tableName = "TEST"; 
                 // Create table 
                 String createTableSQL = "CREATE TABLE IF NOT EXISTS TEST(id integer not null primary key, name varchar, account char(6), birth date)"; 
               
                 // Delete table 
                 String dropTableSQL = "DROP TABLE TEST"; 
               
                 // Insert 
                 String upsertSQL = "UPSERT INTO TEST VALUES(1,'John','100000', TO_DATE('1980-01-01','yyyy-MM-dd'))"; 
               
                 // Query 
                 String querySQL = "SELECT * FROM TEST WHERE id = ?"; 
               
                 // Create the Configuration instance 
                 Configuration conf = getConfiguration(); 
                  
                 // Get URL 
                 String URL = getURL(conf); 
               
                 Connection conn = null; 
                 PreparedStatement preStat = null; 
                 Statement stat = null; 
                 ResultSet result = null; 
               
                 try 
                 { 
                     // Create Connection 
                     conn = DriverManager.getConnection(URL); 
                     // Create Statement 
                     stat = conn.createStatement(); 
                     // Execute Create SQL 
                     stat.executeUpdate(createTableSQL); 
                     // Execute Update SQL 
                     stat.executeUpdate(upsertSQL); 
                     // Create PrepareStatement 
                     preStat = conn.prepareStatement(querySQL); 
                     // Execute query 
                     preStat.setInt(1,1); 
                     result = preStat.executeQuery(); 
                     // Get result 
                     while (result.next())  
                     { 
                         int id = result.getInt("id"); 
                         String name = result.getString(1); 
                     } 
                 }  
                 catch (Exception e) 
                 { 
                     // handler exception 
                 } 
                 finally 
                 { 
                     if(null != result){ 
                          try { 
                              result.close(); 
                              } catch (Exception e2) { 
                                  // handler exception 
                                  } 
                          } 
                     if(null != stat){ 
                         try { 
                             stat.close(); 
                          } catch (Exception e2) { 
                              // handler exception 
                          } 
                     } 
                     if(null != conn){ 
                         try { 
                             conn.close(); 
                          } catch (Exception e2) { 
                              // handler exception 
                          } 
                     } 
                  } 
              }

Precautions

  • A temporary directory for storing intermediate query results must be configured in hbase-site.xml. The size of the query result set is restricted by the directory size.
  • Phoenix implements most java.sql interfaces. SQL follows the ANSI SQL standard.
  • For versions later than MRS 1.9.2, download and configure the open source phoenix package by referring to HBase Phoenix APIs.