Question

由于序列问题，我无法保留任何实体。我使用Glssfish 4，Postgres 9.3 + JPA + EJB3和Netbeans 8。在摘要之下：

    Finest:   persist() operation called on: MyUser{id=null, email=a@e.it, password=test,         firstname=test, lastname=test, company=Test}.
    Finest:   Execute query ValueReadQuery(sql="select nextval('mom_seq_id')")
    Finest:   Connection acquired from connection pool [read].
    Finest:   reconnecting to external connection pool
    Fine:   select nextval(mom_seq_id)
    Finest:   Connection released to connection pool [read].
    Warning:   Local Exception Stack: 
    Exception [EclipseLink-7027] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
    Exception Description: The sequence named [mom_seq_id] is setup incorrectly.  Its increment does not match its pre-allocation size.
at org.eclipse.persistence.exceptions.ValidationException.sequenceSetupIncorrectly(ValidationException.java:1604)
at org.eclipse.persistence.sequencing.StandardSequence.createVector(StandardSequence.java:96)
    ...

Postgres上的序列：

CREATE SEQUENCE my_seq_id
  INCREMENT 1
  MINVALUE 1
  MAXVALUE 9223372036854775807
  START 27
  CACHE 1;
ALTER TABLE my_seq_id
  OWNER TO postgres;
COMMENT ON SEQUENCE my_seq_id
  IS 'Sequence for autoincrement id on MyClass';

我的实体的摘录：

@Entity
@Table(name = "myuser")
@XmlRootElement
public class MyUser implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@SequenceGenerator(name="MYSEQ",
                   sequenceName="my_seq_id")
@GeneratedValue(strategy = GenerationType.SEQUENCE,
                generator="MYSEQ")
@Basic(optional = false)
@Column(name = "id")
private Integer id;

任何人都可以解释什么是错的吗？感谢

我解决了我的问题，但我不知道为什么！我看到allocationSize（）的默认值是50：

package javax.persistence;

@Target(value = {ElementType.TYPE, ElementType.METHOD, ElementType.FIELD})
@Retention(value = RetentionPolicy.RUNTIME)
public @interface SequenceGenerator {

    public String name();

    public String sequenceName() default "";

    public String catalog() default "";

    public String schema() default "";

    public int initialValue() default 1;

    public int allocationSize() default 50;
}

我已将Postgres序列increment_by的值从1更新为50，现在可以正常工作了！

Answer 1

将INCREMENT的值从1改为50到我的Postgres序列解决了这个问题。正如@unwichtich所建议的那样，最好通过@SequenceGenerator注释指定allocationSize = 50属性。

Answer 2

出于我理解的原因，JPA规范选择了50作为序列生成器的默认增量。

PostgreSQL默认为1。

如果两者不匹配，事情变得丑陋，因为JPA认为它可以使用别人也认为已分配的值。至少EclipseLink会检测到这一点; Hibernate只是继续尝试重新使用已经分配的密钥。

如果你的序列是：

CREATE SEQUENCE my_seq_id
  INCREMENT 1

然后您的映射必须反映出：

@SequenceGenerator(name="MYSEQ",
                   sequenceName="my_seq_id", allocationSize=1)

我强烈建议明确说明增量，即使你将它保留为默认值50并改为改变PostgreSQL序列。在稍后调试时，它会保存您和他人的理智。

JPA和Postgres序列预分配大小设置不正确

2 个答案: