SQL Bigint Identity Columns with Hibernate Annotations

Hibernate happily maps SQL bigint identity columns to java.math.BigInteger but then bombs when you try to generate values for this identity, claiming:

org.hibernate.id.IdentifierGenerationException: this id generator generates long, integer, short or string

The solution to this discrepancy is to define your own custom identity value generator. First, create a Java class that extends org.hibernate.id.IdentityGenerator. Two things happen in this class: you hijack the default delegate when Hibernate asks for it and you replace it with your own custom delegate. You then hijack the delegate’s behavior, and prevent it from invoking org.hibernate.id.IdentifierGeneratorFactory‘s static helper methods.

package com.domain.project.hibernate;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.hibernate.HibernateException;
import org.hibernate.dialect.Dialect;
import org.hibernate.id.IdentityGenerator;
import org.hibernate.id.PostInsertIdentityPersister;
import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;

public class BigIntGenerator extends IdentityGenerator {

public static class BigIntDelegate extends GetGeneratedKeysDelegate {
public BigIntDelegate(PostInsertIdentityPersister arg0, Dialect arg1) {
super(arg0, arg1);
}

@Override
public Serializable executeAndExtract(PreparedStatement insert)
throws SQLException {
insert.executeUpdate();
ResultSet rs = null;
try {
rs = insert.getGeneratedKeys();
if (!rs.next()) {
throw new HibernateException( "The database returned no natively generated identity value" );
}
return rs.getBigDecimal(1).toBigIntegerExact();
// ...or whatever type your identity field is
} finally {
if (rs != null) rs.close();
}
}
}

@Override
public InsertGeneratedIdentifierDelegate getInsertGeneratedIdentifierDelegate(
PostInsertIdentityPersister persister, Dialect dialect,
boolean isGetGeneratedKeysEnabled) throws HibernateException {
InsertGeneratedIdentifierDelegate d =
super.getInsertGeneratedIdentifierDelegate(persister, dialect, isGetGeneratedKeysEnabled);
if(d instanceof GetGeneratedKeysDelegate) d = new BigIntDelegate(persister, dialect);
return d;
}
}Tell Hibernate to use your custom identity generator with the following annotation:

@GenericGenerator(
name="BigIntGenerator",
strategy="com.domain.project.hibernate.BigIntGenerator"
)
@Entity
@Table(name="Pages")
public class Page implements Cloneable, Serializable {

@Id @GeneratedValue(strategy=GenerationType.AUTO, generator="BigIntGenerator")
@Column(name="PageID", nullable=false)
private BigInteger id;
...
}