MapReduce服务 MRS-创建表:代码样例

时间：2023-11-01 16:19:45

MapReduce服务 MRS

代码样例

以下代码片段在com.huawei.bigdata.hbase.examples包的“HBaseSample”类的testCreateTable方法中。

public void testCreateTable() {             LOG.info("Entering testCreateTable.");             // Specify the table descriptor.             TableDescriptorBuilder htd = TableDescriptorBuilder.newBuilder(tableName);（1）             // Set the column family name to info.             ColumnFamilyDescriptorBuilder hcd = ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes("info"));（2）             // Set data encoding methods, HBase provides DIFF,FAST_DIFF,PREFIX              hcd.setDataBlockEncoding(DataBlockEncoding.FAST_DIFF);             // Set compression methods, HBase provides two default compression             // methods:GZ and SNAPPY             // GZ has the highest compression rate,but low compression and             // decompression effeciency,fit for cold data             // SNAPPY has low compression rate, but high compression and             // decompression effeciency,fit for hot data.             // it is advised to use SNAANPPY             hcd.setCompressionType(Compression.Algorithm.SNAPPY);//注[1]             htd.setColumnFamily(hcd.build());  （3）             Admin admin = null;              try {               // Instantiate an Admin object.               admin = conn.getAdmin();  （4）               if (!admin.tableExists(tableName)) {                 LOG.info("Creating table...");                 admin.createTable(htd.build());//注[2]  （5）                 LOG.info(admin.getClusterMetrics().toString());                 LOG.info(admin.listNamespaceDescriptors().toString());                 LOG.info("Table created successfully.");               } else {                 LOG.warn("table already exists");               }             } catch (IOException e) {                 LOG.error("Create table failed " ,e);             } finally {               if (admin != null) {                 try {                   // Close the Admin object.                   admin.close();                 } catch (IOException e) {                   LOG.error("Failed to close admin " ,e);                 }               }             }             LOG.info("Exiting testCreateTable.");  }

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