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

问题描述

我有一个应用程序用于连接 MySQL ，并且我有 Hibernate config
它就像这样：

 < 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，如果我要连接到 Hive / SparkSQL 相反，这些属性的
等价值是什么？

我对 driver_class 和 url （假设我们使用port 10000 ），但是 dialect be？

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

更新

<我尝试了许多不同的价值观，但都没有成功。 （我还没有
来找出Apache Hive安装使用的是什么metastore，所以这里
我只是做了试错）

  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，从
Hibernate有一个警告说：

  WARN JdbcServicesImpl，main：160  -  \ 
 HHH000341：无法获取连接元数据：\ 
不支持的方法
  

然后代码会在中运行到 NullPointerException


中， org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure（）
（4.2.0.Final中的207行）。

<我下载了Hibernate和t的源代码遵循逻辑。
异常是由于变量
dialect （类型 Dialect ）被确定为 null ，因为
是尝试执行第138行时捕获的异常：

  metaReportsDDLCausesTxnCommit = meta.dataDefinitionCausesTransactionCommit（）; 
  

例外是

  java.sql.SQLException：不支持的方法
  

（导致上述警告消息）

这是否意味着我不能在Apache Hive中使用 Hibernate ？
如果是这样，那就这样吧。 （我想我会有
换出这部分的 Hibernate 实现）
但是我很想知道权威答案
在互联网上，我找不到有力的证据证明
的人一直在使用 Hibernate 成功使用Apache Hive。

解决方案

我认为Hibernate的答案是不 - Hive / SparkSQL没有方言。显然在Hibernate中不支持HiveServer2（即不是Hive Metastore）。我相信这是真实的（95％的置信度）截至目前（2017-10-19）。

在我的情况下，我最终重写了我的代码并替换了Hibernate代码来指导JDBC代码。幸运的是，那里的Hibernate代码只是用于简单的数据库查询（ session.createSQLQuery（））不是严重的ORM，因此这种更改相对容易。

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>
       ...

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

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>

Update

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

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

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

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();

The exception was

java.sql.SQLException: Method not supported

(that caused the above warning message)

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.

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

解决方案

I am answering my own question here.

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).

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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