CODEWITHSUNDEEP
javahibernate
David
David

Reputation: 20063

Why does Hibernate believe @GeneratedValue is fundamentally wrong?

I was just reading the Hibernate documentation and came across the warning on this page

http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/#d0e1150

"Warning The Hibernate team has always felt such a construct as fundamentally wrong. Try hard to fix your data model before using this feature." with regards to Partial identifier generation

Can someone explain to me in a little more detail what is actually wrong with this? Why does Hibernate look down on generated values? Does that include auto incremented values in Hibernate?

Thanks,

Upvotes: 4

Views: 227

Answers (2)

01es
01es

Reputation: 5410

There is a surrogate identifier, which should always be a single property (and thus column) that at the database level is declared a primary key. And there is a business identifier (aka business key), which has business meaning and may consists of several properties (and thus columns).

There is nothing wrong with generating a single surrogate identifier. What the Hibernate team most likely meant is that generation of some parts of a business identifier (in case of multiple properties) is wrong.

Upvotes: 0

Augusto
Augusto

Reputation: 29977

The warning is not about using @GeneratedValue on a class that has only one id field. The warning is about using @GeneratedValue in one column of a composite key, which is a very odd use case (never seen a need for something like this in 12 years).

So the warning is: If you need to use @GeneratedValue in a composite key, then review your model, because there's a big chance that there's something wrong with it.

If you think that this doesn't answer your question, can you provide an example where you might need this feature?

Upvotes: 2

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