Hive，如何檢索所有數據庫的表列

Question

我想在Hive中編寫這個sql請求的等價物：

select * from information_schema.columns where table_schema='database_name'

如何訪問配置單元的Metastore並檢索存儲在特定數據庫中的所有表的所有列？ 我知道我們可以通過describe [table_name]通過表來完成它，但是在同一個請求中是否有數據庫中所有表的所有列？

Answer 1

如果您希望能夠運行返回hive元數據的此類查詢，則可以使用MySQL設置Hive Metastore，Hive中使用的元數據存儲在MySQL的特定帳戶中。

你必須通過CREATE USER 'hive'@'metastorehost' IDENTIFIED BY 'mypassword'來為hive創建一個MySQL CREATE USER 'hive'@'metastorehost' IDENTIFIED BY 'mypassword' 。

然后，您將找到像COLUMNS_VS這樣的COLUMNS_VS其中包含您要查找的信息。

檢索所有表中所有列的示例查詢可以是： SELECT COLUMN_NAME, TBL_NAME FROM COLUMNS_V2 c JOIN TBLS a ON c.CD_ID=a.TBL_ID

或者，您可以通過REST調用WebHCat訪問此信息，請參閱wiki以獲取更多信息。

Answer 2

如何訪問配置單元的Metastore並檢索存儲在特定數據庫中的所有表的所有列？

這是連接HiveMetaStoreClient一種方法，您可以使用方法getTableColumnsInformation獲取列。

在此類中，可以提取所有其他信息（如分區）。 請參閱示例客戶端和示例方法。

import org.apache.hadoop.hive.conf.HiveConf;

// test program
public class Test {
    public static void main(String[] args){

        HiveConf hiveConf = new HiveConf();
        hiveConf.setIntVar(HiveConf.ConfVars.METASTORETHRIFTCONNECTIONRETRIES, 3);
        hiveConf.setVar(HiveConf.ConfVars.METASTOREURIS, "thrift://host:port");

        HiveMetaStoreConnector hiveMetaStoreConnector = new HiveMetaStoreConnector(hiveConf);
        if(hiveMetaStoreConnector != null){
            System.out.print(hiveMetaStoreConnector.getAllPartitionInfo("tablename"));
        }
    }
}


// define a class like this

import com.google.common.base.Joiner;
import com.google.common.collect.Lists;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.metastore.HiveMetaStoreClient;
import org.apache.hadoop.hive.metastore.api.FieldSchema;
import org.apache.hadoop.hive.metastore.api.MetaException;
import org.apache.hadoop.hive.metastore.api.Partition;
import org.apache.hadoop.hive.metastore.api.hive_metastoreConstants;
import org.apache.hadoop.hive.ql.metadata.Hive;
import org.apache.thrift.TException;
import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormatter;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class HiveMetaStoreConnector {
    private HiveConf hiveConf;
    HiveMetaStoreClient hiveMetaStoreClient;

    public HiveMetaStoreConnector(String msAddr, String msPort){
        try {
            hiveConf = new HiveConf();
            hiveConf.setVar(HiveConf.ConfVars.METASTOREURIS, msAddr+":"+ msPort);
            hiveMetaStoreClient = new HiveMetaStoreClient(hiveConf);
        } catch (MetaException e) {
            e.printStackTrace();
            System.err.println("Constructor error");
            System.err.println(e.toString());
            System.exit(-100);
        }
    }

    public HiveMetaStoreConnector(HiveConf hiveConf){
        try {
            this.hiveConf = hiveConf;
            hiveMetaStoreClient = new HiveMetaStoreClient(hiveConf);
        } catch (MetaException e) {
            e.printStackTrace();
            System.err.println("Constructor error");
            System.err.println(e.toString());
            System.exit(-100);
        }
    }

    public String getAllPartitionInfo(String dbName){
        List<String> res = Lists.newArrayList();
        try {
            List<String> tableList = hiveMetaStoreClient.getAllTables(dbName);
            for(String tableName:tableList){
                res.addAll(getTablePartitionInformation(dbName,tableName));
            }
        } catch (MetaException e) {
            e.printStackTrace();
            System.out.println("getAllTableStatistic error");
            System.out.println(e.toString());
            System.exit(-100);
        }

        return Joiner.on("\n").join(res);
    }

    public List<String> getTablePartitionInformation(String dbName, String tableName){
        List<String> partitionsInfo = Lists.newArrayList();
        try {
            List<String> partitionNames = hiveMetaStoreClient.listPartitionNames(dbName,tableName, (short) 10000);
            List<Partition> partitions = hiveMetaStoreClient.listPartitions(dbName,tableName, (short) 10000);
            for(Partition partition:partitions){
                StringBuffer sb = new StringBuffer();
                sb.append(tableName);
                sb.append("\t");
                List<String> partitionValues = partition.getValues();
                if(partitionValues.size()<4){
                    int size = partitionValues.size();
                    for(int j=0; j<4-size;j++){
                        partitionValues.add("null");
                    }
                }
                sb.append(Joiner.on("\t").join(partitionValues));
                sb.append("\t");
                DateTime createDate = new DateTime((long)partition.getCreateTime()*1000);
                sb.append(createDate.toString("yyyy-MM-dd HH:mm:ss"));
                partitionsInfo.add(sb.toString());
            }

        } catch (TException e) {
            e.printStackTrace();
            return Arrays.asList(new String[]{"error for request on" + tableName});
        }

        return partitionsInfo;
    }

    public String getAllTableStatistic(String dbName){
        List<String> res = Lists.newArrayList();
        try {
            List<String> tableList = hiveMetaStoreClient.getAllTables(dbName);
            for(String tableName:tableList){
                res.addAll(getTableColumnsInformation(dbName,tableName));
            }
        } catch (MetaException e) {
            e.printStackTrace();
            System.out.println("getAllTableStatistic error");
            System.out.println(e.toString());
            System.exit(-100);
        }

        return Joiner.on("\n").join(res);
    }

    public List<String> getTableColumnsInformation(String dbName, String tableName){
        try {
            List<FieldSchema> fields = hiveMetaStoreClient.getFields(dbName, tableName);
            List<String> infs = Lists.newArrayList();
            int cnt = 0;
            for(FieldSchema fs : fields){
                StringBuffer sb = new StringBuffer();
                sb.append(tableName);
                sb.append("\t");
                sb.append(cnt);
                sb.append("\t");
                cnt++;
                sb.append(fs.getName());
                sb.append("\t");
                sb.append(fs.getType());
                sb.append("\t");
                sb.append(fs.getComment());
                infs.add(sb.toString());
            }

            return infs;

        } catch (TException e) {
            e.printStackTrace();
            System.out.println("getTableColumnsInformation error");
            System.out.println(e.toString());
            System.exit(-100);
            return null;
        }
    }
}