从Hive源码解读大数据开发为什么可以脱离SQL、Java、Scala

从Hive源码解读大数据开发为什么可以脱离SQL、Java、Scala

前言

【本文适合有一定计算机基础/半年工作经验的读者食用。立个Flg，愿天下不再有肤浅的SQL Boy】

谈到大数据开发，占据绝大多数人口的就是SQL Boy，不接受反驳，毕竟大数据主要就是为机器学习和统计报表服务的，自然从Oracle数据库开发转过来并且还是只会写几句SQL的人不在少数，个别会Python写个spark.sql(“一个sql字符串”)的已经是SQL Boy中的人才。这种只能处理结构化表的最基础的大数据开发人员，就是我们常提到的梗：肤浅的SQL Boy。。。对大数据完全不懂，思想还停留在数据库时代，大数据组件也都是拿来当RDBMS来用。。。这种业务开发人员的技术水平其实不敢恭维。

还有从Java后端开发转过来的，虽然不适应，但还是可以一个Main方法流畅地操作Spark、Flink，手写个JDBC，做点简单的二开，这种就是平台开发人员，技术水平要更高一些。Java写得好，Scala其实上手也快。

但是。。。这并不代表做大数据只能用SQL/Java/Scala。。。这么局限的话，也不比SQL Boy强到哪里去。

笔者最早还搞过嵌入式开发，自然明白C/C#/C++也可以搞大数据。。。

本文将以大数据开发中最常见的数仓组件Hive的drop table为例，抛砖引玉，解读为神马大数据开发可以脱离SQL、Java、Scala。

为神马可以脱离SQL

数据不外乎结构化数据和非结构化数据，SQL只能处理极其有限的结构化表【RDBMS、整齐的csv/tsv等】，绝大多数的半结构化、非结构化数据SQL是无能为力的【log日志文件、音图等】。古代的MapReduce本身就不可以用SQL，Spark和Flink老版本都是基于API的，没有SQL的年代大家也活得好好的。大数据组件对SQL的支持日渐友好都是后来的事情，主要是为了降低门槛，让SQL Boy也可以用上大数据技术。

肤浅的SQL Boy们当然只知道：

drop table db_name.tb_name;

正常情况这个Hive表就会被drop掉，认知也就局限于Hive是个数据库。

但是大数据平台开发知道去翻看Hive的Java API：

https://svn.apache.org/repos/infra/websites/production/hive/content/javadocs/r3.1.3/api/index.html

知道还有这种方式：

package com.zhiyong;import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.metastore.HiveMetaStoreClient;/*** @program: zhiyong_study* @description: 测试MetaStore* @author: zhiyong* @create: 2023-03-22 22:57**/
public class MetaStoreDemo {public static void main(String[] args) throws Exception{HiveConf hiveConf = new HiveConf();HiveMetaStoreClient client = new HiveMetaStoreClient(hiveConf);client.dropTable("db_name","tb_name");}
}

通过调用API的方式，同样可以drop掉表。显然不一定要用DDL。通过HiveMetaStoreClient的方式，还可以create建表等操作。

懂大数据底层的平台开发当然还有更狠的方式：直接连Hive存元数据的MySQL，对元数据表的数据做精准crud。。。

对结构化表的ETL或者其它的运算处理完全可以用Spark的DataFrame、Flink的DataStream编程，纯API方式实现，SQL能实现的Java和Scala都能实现，至于SQL实现不了的Java和Scala也能实现。。。

笔者实在是想不到除了RDBMS和各类包皮产品【在开源的Apache组件基础上做一些封装】，还有哪些场景是只能用SQL的。。。

至此，可以说明大数据可以脱离SQL。

为神马可以脱离Java

虽然Hive底层是Java写的，但是这并不意味着只能用Java操作Hive。认知这么肤浅的话，也就活该一辈子调参调API了。。。

找到dropTable的实际入口

从Hive3.1.2源码，可以找到dropTable方法：

@Overridepublic void dropTable(String dbname, String name, boolean deleteData,boolean ignoreUnknownTab) throws MetaException, TException,NoSuchObjectException, UnsupportedOperationException {dropTable(getDefaultCatalog(conf), dbname, name, deleteData, ignoreUnknownTab, null);}@Overridepublic void dropTable(String dbname, String name, boolean deleteData,boolean ignoreUnknownTab, boolean ifPurge) throws TException {dropTable(getDefaultCatalog(conf), dbname, name, deleteData, ignoreUnknownTab, ifPurge);}@Overridepublic void dropTable(String dbname, String name) throws TException {dropTable(getDefaultCatalog(conf), dbname, name, true, true, null);}@Overridepublic void dropTable(String catName, String dbName, String tableName, boolean deleteData,boolean ignoreUnknownTable, boolean ifPurge) throws TException {//build new environmentContext with ifPurge;EnvironmentContext envContext = null;if(ifPurge){Map<String, String> warehouseOptions;warehouseOptions = new HashMap<>();warehouseOptions.put("ifPurge", "TRUE");envContext = new EnvironmentContext(warehouseOptions);}dropTable(catName, dbName, tableName, deleteData, ignoreUnknownTable, envContext);}

虽然有多个同名方法，但是底层调用的还是同一个方法：

  /*** Drop the table and choose whether to: delete the underlying table data;* throw if the table doesn't exist; save the data in the trash.** @param catName catalog name* @param dbname database name* @param name table name* @param deleteData*          delete the underlying data or just delete the table in metadata* @param ignoreUnknownTab*          don't throw if the requested table doesn't exist* @param envContext*          for communicating with thrift* @throws MetaException*           could not drop table properly* @throws NoSuchObjectException*           the table wasn't found* @throws TException*           a thrift communication error occurred* @throws UnsupportedOperationException*           dropping an index table is not allowed* @see org.apache.hadoop.hive.metastore.api.ThriftHiveMetastore.Iface#drop_table(java.lang.String,*      java.lang.String, boolean)*/public void dropTable(String catName, String dbname, String name, boolean deleteData,boolean ignoreUnknownTab, EnvironmentContext envContext) throws MetaException, TException,NoSuchObjectException, UnsupportedOperationException {Table tbl;try {tbl = getTable(catName, dbname, name);} catch (NoSuchObjectException e) {if (!ignoreUnknownTab) {throw e;}return;}HiveMetaHook hook = getHook(tbl);if (hook != null) {hook.preDropTable(tbl);}boolean success = false;try {drop_table_with_environment_context(catName, dbname, name, deleteData, envContext);if (hook != null) {hook.commitDropTable(tbl, deleteData || (envContext != null && "TRUE".equals(envContext.getProperties().get("ifPurge"))));}success=true;} catch (NoSuchObjectException e) {if (!ignoreUnknownTab) {throw e;}} finally {if (!success && (hook != null)) {hook.rollbackDropTable(tbl);}}}

主要就是获取了表对象，然后做了preDropTable预提交和commitDropTable实际的提交。这种2PC方式表面上还是很严谨。。。

可以发现HiveMetaHook这其实是个接口：

package org.apache.hadoop.hive.metastore;/*** HiveMetaHook defines notification methods which are invoked as part* of transactions against the metastore, allowing external catalogs* such as HBase to be kept in sync with Hive's metastore.**<p>** Implementations can use {@link MetaStoreUtils#isExternalTable} to* distinguish external tables from managed tables.*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public interface HiveMetaHook {public String ALTER_TABLE_OPERATION_TYPE = "alterTableOpType";public List<String> allowedAlterTypes = ImmutableList.of("ADDPROPS", "DROPPROPS");/*** Called before a table definition is removed from the metastore* during DROP TABLE.** @param table table definition*/public void preDropTable(Table table)throws MetaException;/*** Called after failure removing a table definition from the metastore* during DROP TABLE.** @param table table definition*/public void rollbackDropTable(Table table)throws MetaException;/*** Called after successfully removing a table definition from the metastore* during DROP TABLE.** @param table table definition** @param deleteData whether to delete data as well; this should typically* be ignored in the case of an external table*/public void commitDropTable(Table table, boolean deleteData)throws MetaException;
}

继承关系：

显然不是这个：

package org.apache.hadoop.hive.metastore;public abstract class DefaultHiveMetaHook implements HiveMetaHook {/*** Called after successfully INSERT [OVERWRITE] statement is executed.* @param table table definition* @param overwrite true if it is INSERT OVERWRITE** @throws MetaException*/public abstract void commitInsertTable(Table table, boolean overwrite) throws MetaException;/*** called before commit insert method is called* @param table table definition* @param overwrite true if it is INSERT OVERWRITE** @throws MetaException*/public abstract void preInsertTable(Table table, boolean overwrite) throws MetaException;/*** called in case pre commit or commit insert fail.* @param table table definition* @param overwrite true if it is INSERT OVERWRITE** @throws MetaException*/public abstract void rollbackInsertTable(Table table, boolean overwrite) throws MetaException;
}

更不可能是这个test的Mock类：

/*** Mock class used for unit testing.* {@link org.apache.hadoop.hive.ql.lockmgr.TestDbTxnManager2#testLockingOnInsertIntoNonNativeTables()}*/
public class StorageHandlerMock extends DefaultStorageHandler {}

所以是AccumuloStorageHandler这个类：

package org.apache.hadoop.hive.accumulo;/*** Create table mapping to Accumulo for Hive. Handle predicate pushdown if necessary.*/
public class AccumuloStorageHandler extends DefaultStorageHandler implements HiveMetaHook,HiveStoragePredicateHandler {}

但是：

  @Overridepublic void preDropTable(Table table) throws MetaException {// do nothing}

这个do nothing！！！一言难尽。这种2PC方式表面上确实很严谨。。。

所以dropTable的入口是：

  @Overridepublic void commitDropTable(Table table, boolean deleteData) throws MetaException {String tblName = getTableName(table);if (!isExternalTable(table)) {try {if (deleteData) {TableOperations tblOpts = connectionParams.getConnector().tableOperations();if (tblOpts.exists(tblName)) {tblOpts.delete(tblName);}}} catch (AccumuloException e) {throw new MetaException(StringUtils.stringifyException(e));} catch (AccumuloSecurityException e) {throw new MetaException(StringUtils.stringifyException(e));} catch (TableNotFoundException e) {throw new MetaException(StringUtils.stringifyException(e));}}}

按照最简单的内部表、需要删数据来看，实际上调用的是这个delete方法。而TableOperations又是个接口：

package org.apache.accumulo.core.client.admin;/*** Provides a class for administering tables**/public interface TableOperations {/*** Delete a table** @param tableName*          the name of the table* @throws AccumuloException*           if a general error occurs* @throws AccumuloSecurityException*           if the user does not have permission* @throws TableNotFoundException*           if the table does not exist*/void delete(String tableName) throws AccumuloException, AccumuloSecurityException, TableNotFoundException;
}

继承关系简单：

当然就是这个实现类：

package org.apache.accumulo.core.client.impl;public class TableOperationsImpl extends TableOperationsHelper {@Overridepublic void delete(String tableName) throws AccumuloException, AccumuloSecurityException, TableNotFoundException {checkArgument(tableName != null, "tableName is null");List<ByteBuffer> args = Arrays.asList(ByteBuffer.wrap(tableName.getBytes(UTF_8)));Map<String,String> opts = new HashMap<>();try {doTableFateOperation(tableName, TableNotFoundException.class, FateOperation.TABLE_DELETE, args, opts);} catch (TableExistsException e) {// should not happenthrow new AssertionError(e);}}
}

所以实际入口是这里的doTableFateOperation方法。枚举体的FateOperation.TABLE_DELETE=2。

找到doTableFateOperation方法的调用栈

跳转到：

  private void doTableFateOperation(String tableOrNamespaceName, Class<? extends Exception> namespaceNotFoundExceptionClass, FateOperation op,List<ByteBuffer> args, Map<String,String> opts) throws AccumuloSecurityException, AccumuloException, TableExistsException, TableNotFoundException {try {doFateOperation(op, args, opts, tableOrNamespaceName);} }

继续跳转：

  String doFateOperation(FateOperation op, List<ByteBuffer> args, Map<String,String> opts, String tableOrNamespaceName) throws AccumuloSecurityException,TableExistsException, TableNotFoundException, AccumuloException, NamespaceExistsException, NamespaceNotFoundException {return doFateOperation(op, args, opts, tableOrNamespaceName, true);}

继续跳转：

  String doFateOperation(FateOperation op, List<ByteBuffer> args, Map<String,String> opts, String tableOrNamespaceName, boolean wait)throws AccumuloSecurityException, TableExistsException, TableNotFoundException, AccumuloException, NamespaceExistsException, NamespaceNotFoundException {Long opid = null;try {opid = beginFateOperation();executeFateOperation(opid, op, args, opts, !wait);if (!wait) {opid = null;return null;}String ret = waitForFateOperation(opid);return ret;} catch (ThriftSecurityException e) {switch (e.getCode()) {case TABLE_DOESNT_EXIST:throw new TableNotFoundException(null, tableOrNamespaceName, "Target table does not exist");case NAMESPACE_DOESNT_EXIST:throw new NamespaceNotFoundException(null, tableOrNamespaceName, "Target namespace does not exist");default:String tableInfo = Tables.getPrintableTableInfoFromName(context.getInstance(), tableOrNamespaceName);throw new AccumuloSecurityException(e.user, e.code, tableInfo, e);}} catch (ThriftTableOperationException e) {switch (e.getType()) {case EXISTS:throw new TableExistsException(e);case NOTFOUND:throw new TableNotFoundException(e);case NAMESPACE_EXISTS:throw new NamespaceExistsException(e);case NAMESPACE_NOTFOUND:throw new NamespaceNotFoundException(e);case OFFLINE:throw new TableOfflineException(context.getInstance(), Tables.getTableId(context.getInstance(), tableOrNamespaceName));default:throw new AccumuloException(e.description, e);}} catch (Exception e) {throw new AccumuloException(e.getMessage(), e);} finally {Tables.clearCache(context.getInstance());// always finish table op, even when exceptionif (opid != null)try {finishFateOperation(opid);} catch (Exception e) {log.warn(e.getMessage(), e);}}}

在这里可以发现一些奇怪的现象，居然catch了好多Thrift相关的Exception。继续跳转：

  // This method is for retrying in the case of network failures; anything else it passes to the caller to deal withprivate void executeFateOperation(long opid, FateOperation op, List<ByteBuffer> args, Map<String,String> opts, boolean autoCleanUp)throws ThriftSecurityException, TException, ThriftTableOperationException {while (true) {MasterClientService.Iface client = null;try {client = MasterClient.getConnectionWithRetry(context);client.executeFateOperation(Tracer.traceInfo(), context.rpcCreds(), opid, op, args, opts, autoCleanUp);break;} catch (TTransportException tte) {log.debug("Failed to call executeFateOperation(), retrying ... ", tte);UtilWaitThread.sleep(100);} finally {MasterClient.close(client);}}}

这个死循环里获取了Client对象。但是这个Client一看就没那么简单。。。调用的executeFateOperation方法还不能直接Idea点开，需要手动定位。

分析client对象

package org.apache.accumulo.core.client.impl;import com.google.common.net.HostAndPort;public class MasterClient {private static final Logger log = LoggerFactory.getLogger(MasterClient.class);public static MasterClientService.Client getConnectionWithRetry(ClientContext context) {while (true) {MasterClientService.Client result = getConnection(context);if (result != null)return result;UtilWaitThread.sleep(250);}}
}

实际上又是这个：

public static class Client extends FateService.Client implements Iface {
}

所以其父类是：

package org.apache.accumulo.core.master.thrift;@SuppressWarnings({"unchecked", "serial", "rawtypes", "unused"}) public class FateService {public interface Iface {public void executeFateOperation(org.apache.accumulo.core.trace.thrift.TInfo tinfo, org.apache.accumulo.core.security.thrift.TCredentials credentials, long opid, FateOperation op, List<ByteBuffer> arguments, Map<String,String> options, boolean autoClean) throws org.apache.accumulo.core.client.impl.thrift.ThriftSecurityException, org.apache.accumulo.core.client.impl.thrift.ThriftTableOperationException, org.apache.thrift.TException;}public void executeFateOperation(org.apache.accumulo.core.trace.thrift.TInfo tinfo, org.apache.accumulo.core.security.thrift.TCredentials credentials, long opid, FateOperation op, List<ByteBuffer> arguments, Map<String,String> options, boolean autoClean) throws org.apache.accumulo.core.client.impl.thrift.ThriftSecurityException, org.apache.accumulo.core.client.impl.thrift.ThriftTableOperationException, org.apache.thrift.TException
{send_executeFateOperation(tinfo, credentials, opid, op, arguments, options, autoClean);recv_executeFateOperation();
}public static class Client extends org.apache.thrift.TServiceClient implements Iface {}
}

所以这种client对象才可以执行executeFateOperation方法。

查看executeFateOperation方法

分为2步，字面意思send_executeFateOperation方法发送了啥，recv_executeFateOperation方法又接收了啥。显然发送消息是需要重点关心的：

public void send_executeFateOperation(org.apache.accumulo.core.trace.thrift.TInfo tinfo, org.apache.accumulo.core.security.thrift.TCredentials credentials, long opid, FateOperation op, List<ByteBuffer> arguments, Map<String,String> options, boolean autoClean) throws org.apache.thrift.TException
{executeFateOperation_args args = new executeFateOperation_args();args.setTinfo(tinfo);args.setCredentials(credentials);args.setOpid(opid);args.setOp(op);args.setArguments(arguments);args.setOptions(options);args.setAutoClean(autoClean);sendBase("executeFateOperation", args);
}

这个发送的方法把入参的表名、操作类型【Drop表】设置为sendBase方法的入参。

package org.apache.thrift;/*** A TServiceClient is used to communicate with a TService implementation* across protocols and transports.*/
public abstract class TServiceClient {protected void sendBase(String methodName, TBase<?,?> args) throws TException {sendBase(methodName, args, TMessageType.CALL);}private void sendBase(String methodName, TBase<?,?> args, byte type) throws TException {oprot_.writeMessageBegin(new TMessage(methodName, type, ++seqid_));args.write(oprot_);oprot_.writeMessageEnd();oprot_.getTransport().flush();}}

其中：

package org.apache.thrift.protocol;/*** Message type constants in the Thrift protocol.**/
public final class TMessageType {public static final byte CALL  = 1;public static final byte REPLY = 2;public static final byte EXCEPTION = 3;public static final byte ONEWAY = 4;
}

这个type传入的其实是1。用于构造方法：

package org.apache.thrift.protocol;/*** Helper class that encapsulates struct metadata.**/
public final class TMessage {public TMessage(String n, byte t, int s) {name = n;type = t;seqid = s;}public final String name;public final byte type;public final int seqid;}

另一个泛型TBase：

package org.apache.thrift;import java.io.Serializable;import org.apache.thrift.protocol.TProtocol;/*** Generic base interface for generated Thrift objects.**/
public interface TBase<T extends TBase<?,?>, F extends TFieldIdEnum> extends Comparable<T>,  Serializable {/*** Reads the TObject from the given input protocol.** @param iprot Input protocol*/public void read(TProtocol iprot) throws TException;/*** Writes the objects out to the protocol** @param oprot Output protocol*/public void write(TProtocol oprot) throws TException;
}

按照注释可以知道write方法是把Java的对象输出给协议。

而executeFateOperation_args类：

public static class executeFateOperation_args implements org.apache.thrift.TBase<executeFateOperation_args, executeFateOperation_args._Fields>, java.io.Serializable, Cloneable, Comparable<executeFateOperation_args>   {
public void write(org.apache.thrift.protocol.TProtocol oprot) throws org.apache.thrift.TException {schemes.get(oprot.getScheme()).getScheme().write(oprot, this);}   
}

它的write方法：

package org.apache.thrift.scheme;import org.apache.thrift.TBase;public interface IScheme<T extends TBase> {public void read(org.apache.thrift.protocol.TProtocol iproto, T struct) throws org.apache.thrift.TException;public void write(org.apache.thrift.protocol.TProtocol oproto, T struct) throws org.apache.thrift.TException;}

又是跳转到接口。。。

可以看到有2大抽象类。

而getScheme拿到的：

package org.apache.thrift.protocol;import java.nio.ByteBuffer;import org.apache.thrift.TException;
import org.apache.thrift.scheme.IScheme;
import org.apache.thrift.scheme.StandardScheme;
import org.apache.thrift.transport.TTransport;/*** Protocol interface definition.**/
public abstract class TProtocol {public Class<? extends IScheme> getScheme() {return StandardScheme.class;}public abstract void writeMessageBegin(TMessage message) throws TException;
}

显然get到的是StandardScheme类。而writeMessageBegin又是这个抽象类的抽象方法。

该抽象类的继承关系：

至此可以知道原生支持的协议有这些。最常用的当然就是二进制协议：TBinaryProtocol。

查看TBinaryProtocol二进制协议

package org.apache.thrift.protocol;import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;import org.apache.thrift.TException;
import org.apache.thrift.transport.TTransport;/*** Binary protocol implementation for thrift.**/
public class TBinaryProtocol extends TProtocol {public void writeMessageBegin(TMessage message) throws TException {if (strictWrite_) {int version = VERSION_1 | message.type;writeI32(version);writeString(message.name);writeI32(message.seqid);} else {writeString(message.name);writeByte(message.type);writeI32(message.seqid);}}
}

可以看出writeMessageBegin方法就是实际的写数据操作，把消息拆分后写出。

public void writeString(String str) throws TException {try {byte[] dat = str.getBytes("UTF-8");writeI32(dat.length);trans_.write(dat, 0, dat.length);} catch (UnsupportedEncodingException uex) {throw new TException("JVM DOES NOT SUPPORT UTF-8");}
}

以此为例。会去把数据作为字节数组写出：

package org.apache.thrift.transport;import java.io.Closeable;/*** Generic class that encapsulates the I/O layer. This is basically a thin* wrapper around the combined functionality of Java input/output streams.**/
public abstract class TTransport implements Closeable {/*** Reads up to len bytes into buffer buf, starting at offset off.** @param buf Array to read into* @param off Index to start reading at* @param len Maximum number of bytes to read* @return The number of bytes actually read* @throws TTransportException if there was an error reading data*/public abstract int read(byte[] buf, int off, int len)throws TTransportException;/*** Writes up to len bytes from the buffer.** @param buf The output data buffer* @param off The offset to start writing from* @param len The number of bytes to write* @throws TTransportException if there was an error writing data*/public abstract void write(byte[] buf, int off, int len)throws TTransportException;
}

这才是真正的传输对象。其继承关系：

搞过嵌入式开发的一定很熟悉这个Socket！！！就是IP+port的那个Socket。应用层与TCP/IP传输层间的抽象层。。。

查看TIOStreamTransport传输类

package org.apache.thrift.transport;/*** This is the most commonly used base transport. It takes an InputStream* and an OutputStream and uses those to perform all transport operations.* This allows for compatibility with all the nice constructs Java already* has to provide a variety of types of streams.**/
public class TIOStreamTransport extends TTransport {public int read(byte[] buf, int off, int len) throws TTransportException {if (inputStream_ == null) {throw new TTransportException(TTransportException.NOT_OPEN, "Cannot read from null inputStream");}int bytesRead;try {bytesRead = inputStream_.read(buf, off, len);} catch (IOException iox) {throw new TTransportException(TTransportException.UNKNOWN, iox);}if (bytesRead < 0) {throw new TTransportException(TTransportException.END_OF_FILE);}return bytesRead;}/*** Writes to the underlying output stream if not null.*/public void write(byte[] buf, int off, int len) throws TTransportException {if (outputStream_ == null) {throw new TTransportException(TTransportException.NOT_OPEN, "Cannot write to null outputStream");}try {outputStream_.write(buf, off, len);} catch (IOException iox) {throw new TTransportException(TTransportException.UNKNOWN, iox);}}/*** Flushes the underlying output stream if not null.*/public void flush() throws TTransportException {if (outputStream_ == null) {throw new TTransportException(TTransportException.NOT_OPEN, "Cannot flush null outputStream");}try {outputStream_.flush();} catch (IOException iox) {throw new TTransportException(TTransportException.UNKNOWN, iox);}}
}

其子类TSocket重写了IP、Port和init等。

小结Drop表的流程

至此可以得知Java用API操作Hive的原理，大致是这样：

顶层API【dropTable】→表操作实现类【TableOperationsImpl】的删表方法【doTableFateOperation】
→executeFateOperation方法→Client类的实例对象的executeFateOperation方法
→sendBase方法→executeFateOperation_args静态类的实例对象的write方法输出数据给传输协议TProtocol
→传输协议类的write方法具体把数据写出给Thrift的Server
→Thrift的Server接收到消息后执行对应的操作

最出名的Thrift当然是Hive自己的Hive Server【Standalone】和Hive Server2，还有Spark的Thrift Server，借助它们，可以用JDBC或者Cli的方式去操作Hive。

但是！！！Thrift的初衷就是实现语言无关，毕竟底层只需要能把数据传输到位即可，数据传输并不是Java的特权。

其它语言的Thrift

在service-rpc这个路径下，可以发现有cpp、Java、php、py，rb的包！！！

Hive的官方文档写的很明白：

https://cwiki.apache.org/confluence/display/Hive/HiveClient#HiveClient-ThriftJavaClient

The command line client currently only supports an embedded server. The JDBC and Thrift-Java clients support both embedded and standalone servers. Clients in other languages only support standalone servers.

命令行模式目前只能用于嵌入式服务，JDBC和Thrift-Java的Client可以支持嵌入式和独立部署的服务。别的语言的Client只支持在独立部署的服务使用。

Connection con = DriverManager.getConnection("jdbc:hive://localhost:10000/default", "", "");
Statement stmt = con.createStatement();

这种古代的Hive Server就是嵌入模式。。。

Connection con = DriverManager.getConnection("jdbc:hive2://localhost:10000/default", "", "");

这种Hive Server2就是独立部署模式。

官方还给出了python的案例：

#!/usr/bin/env pythonimport sysfrom hive import ThriftHive
from hive.ttypes import HiveServerException
from thrift import Thrift
from thrift.transport import TSocket
from thrift.transport import TTransport
from thrift.protocol import TBinaryProtocoltry:transport = TSocket.TSocket('localhost', 10000)transport = TTransport.TBufferedTransport(transport)protocol = TBinaryProtocol.TBinaryProtocol(transport)client = ThriftHive.Client(protocol)transport.open()client.execute("CREATE TABLE r(a STRING, b INT, c DOUBLE)")client.execute("LOAD TABLE LOCAL INPATH '/path' INTO TABLE r")client.execute("SELECT * FROM r")while (1):row = client.fetchOne()if (row == None):breakprint rowclient.execute("SELECT * FROM r")print client.fetchAll()transport.close()except Thrift.TException, tx:print '%s' % (tx.message)

以及PHP的案例：

<?php
// set THRIFT_ROOT to php directory of the hive distribution
$GLOBALS['THRIFT_ROOT'] = '/lib/php/';
// load the required files for connecting to Hive
require_once $GLOBALS['THRIFT_ROOT'] . 'packages/hive_service/ThriftHive.php';
require_once $GLOBALS['THRIFT_ROOT'] . 'transport/TSocket.php';
require_once $GLOBALS['THRIFT_ROOT'] . 'protocol/TBinaryProtocol.php';
// Set up the transport/protocol/client
$transport = new TSocket('localhost', 10000);
$protocol = new TBinaryProtocol($transport);
$client = new ThriftHiveClient($protocol);
$transport->open();// run queries, metadata calls etc
$client->execute('SELECT * from src');
var_dump($client->fetchAll());
$transport->close();

Ruby好歹也给了个参考： https://github.com/forward3d/rbhive

至于Java、C++就不给Client的案例了。。。也是很容易理解。。。毕竟Java有JDBC和高层API，一般不会有人去用底层API了。

如果是做平台开发或者组件开发这种真正用得上底层API的情况，地方支援中央发型的老Java程序猿，查API填参数让程序跑起来，这点工程能力还是有的。

至于C++程序猿强悍的造轮子功力，没准像临摹Kafka的Red Panda那样，哪天也照猫画虎折腾出个C++版的Hive。。。

既然可以通过Thrift实现语言无关，那么调用组件就不必局限于Java或者Scala。而造轮子从来也不是Java和Scala的专利。

这就是为神马大数据开发可以脱离Java和Scala。

尾言

大数据并不是趋向SQL化，只是为了扩大受众群体，让广大技术水平不高的业务开发人员也能吃上大数据技术的红利。且SQL在处理结构化表的特定场景下开发效率更高。
但是。。。哪怕是这种极度细分的场景，SQL还是有很多缺陷，虽然API的方式也没有好到哪里去。

造轮子和组件调用，就更是语言无关的事情了。。。编程语言往往只是个表达思想的载体，技术栈足够全面才有做选择的权力。

转载请注明出处：https://lizhiyong.blog.csdn.net/article/details/129742904