大对象不能用于自动提交模式 [英] Large Objects may not be used in auto-commit mode

问题描述

我有一个在PostgreSQL数据库上使用Hibernate的Spring应用程序。我试图将文件存储在数据库的表中。看起来它存储行与文件（我只是在EntityManager上使用persist方法），但是当从数据库加载对象时，我得到以下异常：

  org.postgresql.util.PSQLException：大对象不能用于自动提交模式。 
  

为了加载数据，我使用了MultipartFile transient属性，并在其setter中设置了我想要坚持的信息（字节[]，文件名，大小）。
我坚持的实体看起来像这样（我已经省略了getters / setters的其余部分）：

  @Entity 
 @Table（name =myobjects）
 public class MyClass {
 
 @Id 
 @GeneratedValue（strategy = GenerationType.SEQUENCE，generator =序列）
 @SequenceGenerator（name =sequence，sequenceName =myobjects_pk_seq，allocationSize = 1）
 @Column（name =id）
 private Integer id; 
 
 @Lob 
私有字符串描述; 
 
 @Temporal（TemporalType.TIMESTAMP）
私人日期creationDate; 
 
 @Transient 
 private MultipartFile multipartFile; 
 
 @Lob 
 @Basic（fetch = FetchType.LAZY，可选= true）
 byte [] file; 
 
字符串文件名; 
 
 String fileContentType; 
 
整数fileSize; 
 
 public void setMultipartFile（MultipartFile multipartFile）{
 this.multipartFile = multipartFile; 
尝试{
 this.file = this.multipartFile.getBytes（）; 
 this.fileName = this.multipartFile.getOriginalFilename（）; 
 this.fileContentType = this.multipartFile.getContentType（）; 
 this.fileSize =（（Long）this.multipartFile.getSize（））。intValue（）; 
} catch（IOException e）{
 logger.error（e.getStackTrace（））; 
} 
} 
} 
  

我可以看到，是持久的我有行中的数据，但是当我调用这个方法时，它失败了：

  public List< MyClass> findByDescription（String text）{
 Query query = getEntityManager（）。createQuery（from MyClass WHERE UPPER（description）like：query ORDER BY creationDate DESC）; 
 query.setParameter（query，％+ text.toUpperCase（）+％）; 
返回query.getResultList（）; 
} 
  

只有当结果包含带有文件的对象时，此方法才会失败。我尝试在我的persistence.xml中设置

 < property name =hibernate.connection.autocommitvalue =假/> 
  

但它不能解决问题。

通常情况下，应用程序运行良好，只有在事务完成时才提交数据，并且在发生某种情况时会执行回滚，所以我不明白为什么会发生这种情况。

有什么想法？

谢谢。

>

查看Shekhar给出的链接，建议将该调用包含在转换中，因此我在事务内部设置了服务调用（它添加了@

  @Transactional 
 public List< myClass> find（String text）{
 return myClassDAO.findByDescription（text）; 
} 
  

问题是我不想保存任何数据，所以我不会不明白为什么它应该包含在交易中。
$ b

谢谢。

解决方案

大对象可以存储在多个记录中，这就是为什么您必须使用事务。所有记录都是正确的或根本没有。

https://www.postgresql.org/docs/current/static/largeobjects.html

I have a Spring application which uses Hibernate on a PostgreSQL database. I'm trying to store files in a table of the database. It seems it stores the row with the file (I just use persist method on EntityManager), but when the object is loaded from the database I get the following exception:

org.postgresql.util.PSQLException: Large Objects may not be used in auto-commit mode.

To load the data I'm using a MultipartFile transient atribute and in its setter I'm setting the information I want to persist (byte[], fileName, size). The entity I'm persisting looks like this one (I've ommitted the rest of getters/setters):

@Entity
@Table(name="myobjects")
public class MyClass {

    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="sequence")
    @SequenceGenerator(name="sequence", sequenceName="myobjects_pk_seq", allocationSize=1)
    @Column(name="id")
    private Integer id;

    @Lob
    private String description;

    @Temporal(TemporalType.TIMESTAMP)
    private Date creationDate;

    @Transient
    private MultipartFile multipartFile;

    @Lob
    @Basic(fetch=FetchType.LAZY, optional=true)
    byte[] file;

    String fileName;

    String fileContentType;

    Integer fileSize;

    public void setMultipartFile(MultipartFile multipartFile) {
        this.multipartFile = multipartFile;
        try {
            this.file = this.multipartFile.getBytes();
            this.fileName = this.multipartFile.getOriginalFilename();
            this.fileContentType = this.multipartFile.getContentType();
            this.fileSize = ((Long) this.multipartFile.getSize()).intValue();
        } catch (IOException e) {
            logger.error(e.getStackTrace());
        }
    }
}

I can see that when it is persisted I have the data in the row but when I call this method it fails:

public List<MyClass> findByDescription(String text) {
    Query query = getEntityManager().createQuery("from MyClass WHERE UPPER(description) like :query ORDER BY creationDate DESC");
    query.setParameter("query", "%" + text.toUpperCase() + "%");
    return query.getResultList();
}

This method only fails when the result has objects with files. I've tried to set in my persistence.xml

<property name="hibernate.connection.autocommit" value="false" />

but it doesn't solve the problem.

In general the application works well it only commit the data when the transaction is finished and it performs a rollback if something fails, so I don't understand why is this happening.

Any idea?

Thanks.

UPDATE

Looking at the link given by Shekhar it is suggested to include the call in a transation, so I've set the service call inside a transaction an it works (I've added @Transactional annotation).

@Transactional
public List<myClass> find(String text) {
    return myClassDAO.findByDescription(text);
}

the problem is that I don't want to persist any data so I don't understand why it should be include inside a transaction. Does it make any sense to make a commit when I've only loaded some data form the database?

Thanks.

解决方案

A large object can be stored in several records, that's why you have to use a transaction. All records are correct or nothing at all.

https://www.postgresql.org/docs/current/static/largeobjects.html

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