Hbase - 如何获取表中的列名？

Question

我有一些具有数百万行但只有几列的 HBase 表。我想提取每个表的列名并将其存储在一个单独的文件中。做这个的最好方式是什么？ 谢谢。

Answer 1

下面将有助于获取与特定键相关的列

scan 'namespace:tablename',{FILTER=>'KeyOnlyFilter()'}

Answer 2

我会提供由HbaseAdmin 类公开的 java Hbase 客户端 API，如下所示...

客户会喜欢

package mytest;
import com.usertest.*;

import java.io.IOException;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Set;


public class ListHbaseTablesAndColumns {
    public static void main(String[] args) {
        try {
            HbaseMetaData hbaseMetaData  =new HbaseMetaData();
            for(String hbaseTable:hbaseMetaData  .getTableNames(".*yourtables.*")){
                    for (String column : hbaseMetaData  .getColumns(hbaseTable, 10000)) {
                        System.out.println(hbaseTable + "," + column);
                    }
                
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

---

使用下面的类来获取 HbaseMetaData..

package com.usertest;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.filter.PageFilter;

import java.io.IOException;
import java.util.*;
import java.util.regex.Pattern;

public class HbaseMetaData {
    private HBaseAdmin hBaseAdmin;
    private Configuration hBaseConfiguration;

    public HbaseMetaData () throws IOException {
        this.hBaseConfiguration = HBaseConfiguration.create();
        this.hBaseAdmin = new HBaseAdmin(hBaseConfiguration);
    }
/** get all Table names **/
    public List<String> getTableNames(String regex) throws IOException {
        Pattern pattern=Pattern.compile(regex);
        List<String> tableList = new ArrayList<String>();
        TableName[] tableNames=hBaseAdmin.listTableNames();
        for (TableName tableName:tableNames){
            if(pattern.matcher(tableName.toString()).find()){
                tableList.add(tableName.toString());
            }
        }
        return tableList;
    }
/** Get all columns **/
    public Set<String> getColumns(String hbaseTable) throws IOException {
        return getColumns(hbaseTable, 10000);
    }
/** get all columns from the table **/
    public Set<String> getColumns(String hbaseTable, int limitScan) throws IOException {
        Set<String> columnList = new TreeSet<String>();
        HTable hTable=new HTable(hBaseConfiguration, hbaseTable);
        Scan scan=new Scan();
        scan.setFilter(new PageFilter(limitScan));
        ResultScanner results = hTable.getScanner(scan);
        for(Result result:results){
            for(KeyValue keyValue:result.list()){
                columnList.add(
                        new String(keyValue.getFamily()) + ":" +
                                new String(keyValue.getQualifier())
                );
            }
        }
        return columnList;
    }
}

Answer 3

这应该将列名保存在本地（而不是 hdfs）上的 Hbase_table_columns.txt 文件中：

echo "scan 'table_name'" | $HBASE_HOME/bin/hbase shell | awk -F'=' '{print $2}' | awk -F ':' '{print $1}' > Hbase_table_columns.txt

这应该在控制台上保存列名：

echo "scan 'table_name'" | $HBASE_HOME/bin/hbase shell | awk -F'=' '{print $2}' | awk -F ':' '{print $1}'

这应该将列名保存在 Hbase_table_columns.txt 文件中，并在控制台上打印：

echo "scan 'table_name'" | $HBASE_HOME/bin/hbase shell | awk -F'=' '{print $2}' | awk -F ':' '{print $1}' |tee Hbase_table_columns.txt

---

这应该保存/打印column family:column name:

echo "scan 'table_name'" | $HBASE_HOME/bin/hbase shell | awk -F'=' '{print $2}'|tee Hbase_table_columns.txt