Commonly used Generators in ‘Hibernate’

Generator Description
increment It generates identifiers of type long, short or int that are unique only when no other process is inserting data into the same table. It should not the used in the clustered environment.
identity It supports identity columns in DB2, MySQL, MS SQL Server, Sybase and HypersonicSQL. The returned identifier is of type long, short or int.
sequence The sequence generator uses a sequence in DB2, PostgreSQL, Oracle, SAP DB, McKoi or a generator in Interbase. The returned identifier is of type long, short or int
hilo The hilo generator uses a hi/lo algorithm to efficiently generate identifiers of type long, short or int, given a table and column (by default hibernate_unique_key and next_hi respectively) as a source of hi values. The hi/lo algorithm generates identifiers that are unique only for a particular database. Do not use this generator with connections enlisted with JTA or with a user-supplied connection.
seqhilo The seqhilo generator uses a hi/lo algorithm to efficiently generate identifiers of type long, short or int, given a named database sequence.
uuid The uuid generator uses a 128-bit UUID algorithm to generate identifiers of type string, unique within a network (the IP address is used). The UUID is encoded as a string of hexadecimal digits of length 32.
guid It uses a database-generated GUID string on MS SQL Server and MySQL.
native It picks identity, sequence or hilo depending upon the capabilities of the underlying database.
assigned lets the application to assign an identifier to the object before save() is called. This is the default strategy if no <generator> element is specified.
select retrieves a primary key assigned by a database trigger by selecting the row by some unique key and retrieving the primary key value.
foreign uses the identifier of another associated object. Usually used in conjunction with a <one-to-one> primary key association.

Technorati tags: Hibernate Generators, ORM
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4 thoughts on “Commonly used Generators in ‘Hibernate’

  1. Lijin Post author

    Ha ha nice to hear that u want to spend more time with ur gf šŸ™‚
    . She must be luck to get u. And in the case of hibernate, its giving so much easiness for us to do our job in time.

    Reply
  2. Jason

    Heya… You don’t know me, but your blog looked good.

    We did eventually get it done, but unfortunately outside of the deadline. I quit that job about 4 months ago, because my stress levels where to high (and I wanted to spend more time with my girlfriend).

    I harbor no real ill feelings against Hibernate, but after spending lots of time playing with SQL tools, I prefer working more closely with my database.

    Reply
  3. Jason

    I find that UUID’s work best when the database is going to be clustered, since the database doesn’t have to work with locking sequences. That said, I havn’t used Hibernate in a few months due to a project missing a major dealine because of weird bugs somewhere between Spring; Hibernate and XDoclet (we still don’t exactly know where), which has led to me avoiding all three šŸ˜¦

    Reply

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