Hibernate Auto Increment Id

Hibernate Auto Increment ID

private int id;

and you leave it null (0) when persisting. (null if you use the Integer / Long wrappers)

In some cases the AUTO strategy is resolved to SEQUENCE rathen than to IDENTITY or TABLE, so you might want to manually set it to IDENTITY or TABLE (depending on the underlying database).

It seems SEQUENCE + specifying the sequence name worked for you.

How to auto generate primary key ID properly with Hibernate inserting records

You should use IDENTITY generator. The IDENTITY generator allows an integer and bigint column to be auto-incremented on demand. The increment process is very efficient since it uses a database internal lightweight locking mechanism as opposed to the more heavyweight transactional course-grain locks.

@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

And don't use id in the insert statement as it is being generated automatically.

Note that SEQUENCE will not work for you as SEQUENCE does not work with MySQL

What is the Java annotation in Hibernate used to auto increment a MySQL Primary Key - @Id

Although you could use GenerationType.AUTO, it's not a very good idea for MySQL and Hibernate 5 because it will default to the TABLE generator which is bad for performance.

So, although [it will disable JDBC batch inserts][3], you should use IDENTITY:

@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

or you can use native identifier generator which falls back to IDENTITY on MySQL:

strategy= GenerationType.AUTO,
name = "native",
strategy = "native"
private Long id;

Hibernate is generating auto increment alternating id for tables

You haven't specified any generator for any of your entities. So Hibernate uses the default one for your database, which consists in using single sequence: hibernate_sequence, to generate the IDs of the entities.

Annotate your Student id field with something like

@SequenceGenerator(name = "studentGenerator", sequenceName = "STUDENT_SEQUENCE", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "studentGenerator")

and it will use a dedicated sequence, STUDENT_SEQUENCE, for the Student entity. Do the same (with a different generator and sequence name) for the other entities.

Hibernate doesn't auto increment id of entity { Country } ( using h2 data base )

This issue was fixed in Hibernate ORM 5.6.5.Final, an upgrade to this or any newer version is the best way to fix it. Information below is applicable to older versions.

This is a known issue of Hibernate ORM: HHH-14985, it generates invalid SQL for H2 that was accepted by H2 1.x and isn't accepted by default by H2 2.x. It was already fixed in sources of Hibernate ORM, so you need to wait for its next release before trying to use H2 2.0.

You can try to append ;MODE=LEGACY to JDBC URL of H2 as a temporary workaround, in this mode these invalid attempts to insert a NULL value into identity column with implicit NOT NULL constraint don't produce this error.

Unfortunately, you may run into some other incompatibility. In that case you need to downgrade to H2 1.4.200 (and remove that MODE setting).

How does Hibernate get the AutoIncrement Value on Identity Insert

You should call SELECT LAST_INSERT_ID().

Practically, you can't do the same thing as the MySQL JDBC driver using another MySQL client. You'd have to write your own client that reads and writes the MySQL protocol.

The MySQL JDBC driver gets the last insert id by parsing packets of the MySQL protocol. The last insert id is returned in this protocol by a MySQL result set.

This is why SELECT LAST_INSERT_ID() doesn't show up in query metrics. It's not calling that SQL statement, it's picking the integer out of the result set at the protocol level.

You asked how it's done internally. A relevant line of code is https://github.com/mysql/mysql-connector-j/blob/release/8.0/src/main/protocol-impl/java/com/mysql/cj/protocol/a/result/OkPacket.java#L55

Basically, it parses an integer from a known position in a packet as it receives a result set.

I'm not going to go into any more detail about parsing the protocol. I don't have experience coding a MySQL protocol client, and it's not something I wish to do.

I think it would not be a good use of your time to implement your own MySQL client.

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