JdbcTemplate should store generated keys only if database driver supports it

[maciejmiklas]

Not every database supports PreparedStatement#getGeneratedKeys(), for example, SQLLitle does not, and calling this method throws an exception, it has been discussed here: xerial/sqlite-jdbc#996

JdbcTemplate calls PreparedStatement#getGeneratedKeys() whether it's supported or not, and in the case of SQLLitle, it causes an exception.

This PR changes the behavior of JdbcTemplate that it will call PreparedStatement#getGeneratedKeys() only if the underlying driver supports it by querying: DatabaseMetaData#supportsGetGeneratedKeys().

[gotson]

It might be worth reading similar questions asked on jooq's github some years ago, as apparently supportsGetGeneratedKeys may not be reliable in some drivers.

jOOQ/jOOQ#8996 (comment)

There's also jOOQ/jOOQ#8993 (comment) where apparently returning null from getGeneratedKeys, instead an empty resultset should be returned.

[jhoeller]

So your code is calling a JdbcTemplate operation with a KeyHolder argument there but would be happy for that key holder not to be populated? Note that there are non-KeyHolder overloads of those methods which never trigger a getGeneratedKeys call to begin with, in case you do not need those keys anyway.

If we consider key retrieval as sort-of-optional even for our KeyHolder-based operations, we could simply catch SQLFeatureNotSupportedException on actual access, I suppose, just like we check for null there. That would avoid any potential inconsistency with DatabaseMetaData support checks.

However, I'm still concerned by the mismatch with the javadoc for our KeyHolder-based operations which explicitly state that "generated keys will be put into the given KeyHolder". If the JDBC driver does not support key retrieval, arguably those JdbcTemplate operations are meant to fail...

[maciejmiklas]

@jhoeller you are correct - we can use update without keys

[snicoll]

Thanks for the follow-up. I've created #31486 to review the Javadoc.

[prrvchr]

Hi all,
Here is a JDBC 4.1 compatible SQLite version with getGeneratedKeys() support.
sqlite-jdbc-3.45.1.5-SNAPSHOT.jar