java - JPA - INSERT 后的 PK 属性问题

Question

JPA( hibernate 提供程序)和 Postgres 11

我的 Id 属性有此配置(它是单个列/属性 PK)。

由于某种原因，在对该表执行 INSERT 操作后，JPA 调用

选择 currval('yb.asset_store_id_seq')

我猜(我不确定)这样做是为了刷新新插入实体的 ID，或者可能出于某种类似的原因。

但是不存在这样的序列。我的序列名为 yb.asset_store_seq，我的表为 yb.asset_store。 我的实体类是AssetStore。

那么...我该如何解决这个问题呢？基本上JPA 不知何故编造了这个序列名称。或者我错过了什么？!

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", unique = true, nullable = false, insertable=false, updatable=false)
private Integer id;

在数据库级别，序列由表拥有。

这是堆栈跟踪。

    Hibernate: 
        select
            currval('yb.asset_store_id_seq')
    Mar 25, 2020 3:45:02 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
    WARN: SQL Error: 0, SQLState: 42P01
    Mar 25, 2020 3:45:02 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
    ERROR: ERROR: relation "yb.asset_store_id_seq" does not exist
      Position: 16
    Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not extract ResultSet


    ...................


        Caused by: org.postgresql.util.PSQLException: ERROR: relation "yb.asset_store_id_seq" does not exist
  Position: 16
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2440)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2183)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:308)

Answer 1

首先是 hibernate documentation根本不建议使用 GenerationType.IDENTITY 策略:

It is important to realize that using IDENTITY columns imposes a runtime behavior where the entity row must be physically inserted prior to the identifier value being known.

This can mess up extended persistence contexts (long conversations). Because of the runtime imposition/inconsistency, Hibernate suggests other forms of identifier value generation be used (e.g. SEQUENCE).

There is yet another important runtime impact of choosing IDENTITY generation: Hibernate will not be able to batch INSERT statements for the entities using the IDENTITY generation.

但是如果你不能改变它，并且你使用的是JDBC3+驱动程序和JRE1.4+。我建议明确定义:

<property name="hibernate.jdbc.use_get_generated_keys">true</property>

因为根据this

hibernate.jdbc.use_get_generated_keys (e.g. true or false)

Allows Hibernate to use JDBC3 PreparedStatement.getGeneratedKeys() to retrieve natively-generated keys after insert. You need the JDBC3+ driver and JRE1.4+. Disable this property if your driver has problems with the Hibernate identifier generators. By default, it tries to detect the driver capabilities from connection metadata.

它将可以避免您的问题。