Hive/SparkSQL 的 Hibernate 方言? [英] Hibernate dialect for Hive/SparkSQL?

问题描述

我有一个用于连接到 MySQL 的应用程序，并且我有 Hibernate 配置像这样:

I have an app that used to connect to MySQL, and I have Hibernate config for it like this:

<hibernate-configuration>
   <session-factory>
       <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
       <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
       <property name="hibernate.connection.url">jdbc:mysql://somehost:3306/some_db</property>
       ...

现在如果我想连接到 Hive/SparkSQL，这些属性的等效值是什么?

Now if I want to connect to Hive/SparkSQL instead, what would the equivalent values for these properties be?

我对 driver_class 和 url 有一些想法(假设我们使用端口 10000)，但是 dialect 是?

I have some ideas on driver_class and url (assuming we are using port 10000), but what should the dialect be?

<property name="hibernate.connection.driver_class">org.apache.hive.jdbc.HiveDriver</property>
<property name="hibernate.connection.url">jdbc:hive2://someHost:10000</property>

更新

我尝试了许多不同的值，但没有一个有效.(我还没有找出 Apache Hive 安装使用的元存储，所以在这里我只是在反复试验)

I tried many different values but none of them work. (I have yet to find out what metastore the Apache Hive installation uses, so here I was just doing trial-and-error)

org.hibernate.dialect.MySQLDialect
org.hibernate.dialect.MySQLInnoDBDialect
org.hibernate.dialect.DerbyDialect
org.hibernate.dialect.DerbyTenFiveDialect
org.hibernate.dialect.Oracle10gDialect
org.hibernate.dialect.H2Dialect
org.hibernate.dialect.Dialect

我注意到在所有情况下，都有来自休眠说:

I noticed that in all case, there is a warning from Hibernate that said:

WARN JdbcServicesImpl,main:160 - \
  HHH000341: Could not obtain connection metadata : \
  Method not supported

然后代码会遇到NullPointerException
在 org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure()(4.2.0.Final 中的第 207 行).

And then the code would run into a NullPointerException
in org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure() (Line 207 in 4.2.0.Final).

我下载了Hibernate的源代码，并跟踪了逻辑.异常是由于变量前面几行引起的dialect(Dialect 类型)被确定为 null 由于尝试执行第 138 行时捕获的异常:

I downloaded the source code of Hibernate and traced the logic. The exception was caused because a few line ahead a variable dialect (of type Dialect) was determined to be null due to an exception caught when trying to execute Line 138:

metaReportsDDLCausesTxnCommit = meta.dataDefinitionCausesTransactionCommit();

例外是

java.sql.SQLException: Method not supported

(导致上面的警告信息)

(that caused the above warning message)

这是否意味着我不能将 Hibernate 与 Apache Hive 一起使用?如果是这样，那就这样吧.(我想我会有换掉这部分的 Hibernate 实现)但是我很想知道权威的答案

Does that mean I cannot use Hibernate with Apache Hive? If that is the case, then so be it. (I guess I would have to swap out the Hibernate implementation for this part) But I am curious to know the authoritative answer on this.

在互联网上我找不到有力的证据表明人们已经成功地将 Hibernate 与 Apache Hive 结合使用.

On the Internet I could not find strong evidence that people have been using Hibernate successfully with Apache Hive.

推荐答案

我在这里回答我自己的问题.

I am answering my own question here.

我认为 Hibernate 的答案是不——Hive/SparkSQL 没有方言".显然，Hibernate 中不支持 HiveServer2(即不是 Hive Metastore).我相信截至目前(2017-10-19)这是真的(95% 的置信度).

I think the answer is "No -- there is no dialect for Hive/SparkSQL" for Hibernate. Apparently there are no support for HiveServer2 (i.e. not the Hive Metastore) in Hibernate. I believe this is true (95% confidence) as of now (2017-10-19).

就我而言，我最终重写了我的代码并将 Hibernate 代码替换为直接 JDBC 代码.我很幸运，那里的 Hibernate 代码只是用于简单的 DB 查询(session.createSQLQuery())而不是严重的 ORM，因此更改相对容易.

In my case, I ended up rewriting my code and replacing the Hibernate code to direct JDBC code instead. I was lucky that the Hibernate code there was just for simple DB query (session.createSQLQuery()) not serious ORM, so the change was relatively easy.

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