> If I do:
> conn.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);
> or
> conn.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
>
> Does the behavior of the transaction change?

current transaction should be committed (not sure if our driver does
this. David, any comments here?), and new one will have new
transaction isolation. However, TRANSACTION_READ_UNCOMMITTED is not
supported, so your second statement will throw an exception.

> If those methods are not there just to comply with the interface, I'd
> like to see how do the 5 isolation levels present in JDBC map to the
> ones provided in firebird/interbase.

TRANSACTION_SERIALIZABLE - isc_tpb_consistency
TRANSACTION_REPEATABLE_READ - isc_tpb_concurrency
TRANSACTION_READ_COMMITTED - isc_tpb_read_committed & isc_tpb_rec_version
TRANSACTION_READ_UNCOMMITTED - not supported
TRANSACTION_NONE - not supported

> I don't expect a lecture, just point me where to look if there's
> documentatin on this.

Then take a org.firebirdsql.jca.FBTpb source and check the mapping
there. :)

Best regards,
Roman Rokytskyy