Just embarking on this Hibernate journey here.

If I have a column that is defined like so


and the application logic looks like so
I can see that if I inspect the value of the user instance right after the save it has the value of the id that was just inserted. So is hibernate doing a "SELECT" from the database right after the INSERT to retrieve that value?

But reading the manual I get the impression that if there are other columns in the table that are populated by means of triggers or some such, then I need to do a session.refresh() so the user instance has those properties.

And one related question
Is there anything to choose between these two statements
and

Thanks!

When it comes to database-generated columns (e.g IDENTITY), it really depends on the underlying driver capabilities to fetch the newly generated PK value.

The [url=https://docs.oracle.com/javase/7/docs/api/java/sql/DatabaseMetaData.html#generatedKeyAlwaysReturned()]DatabaseMetaData.html#generatedKeyAlwaysReturned()
[/url] tells if the Driver supports retrieving generated key using the very same database rountrip used for executing the statement:



Nevertheless, this might work with JDBC batching or not, which is also a Driver-specific detail. If the JDBC Driver does not support such a construct, Hibernate must use a secondary query to fetch the newly generated identifier.

As for refresh, you only need it if the database generates other columns than the identifier, like when you @Generated.

great, that link helped- in fact there is a response that dovetails with my situation since I'm working with MySQL.

which is presumably why in a further experiment I found that the same "user" instance that I used in the session.save actually had the value of the id populated when I inspected it immediately after the save statement.
Thanks!