Transaction issue with DDL

Question

Is it true that you'll get error trying to execute DDL to a certain table if there's an active transaction to that table? take a look at this case:
insert into t1 values(1,2,3)
drop table t1as you can see, I havent' commited yet, so the transaction to t1 should still be active.
I tried opening a new session in SQL Developer just to confirm that the DML insert hasn't been committed yet
select * from t1and yes, it returned no rows.
I was expecting error, but the
drop table t1didn't produce any error. It executed succesfully. Am I missing something? thanks

Answer 1

You would need to do the INSERT and the DROP in two different sessions in order to generate an error (ORA-00054: resource busy and acquire with NOWAIT specified).
DDL does an implicit commit before and after the DDL is executed. So your DROP statement first commits the INSERT then drops the table and finally issues another commit. That doesn't generate any errors because by the time the table is dropped, there is no active transaction. Additionally, even if there was an active transaction, the you'll never get an error waiting for a lock that your session already has. Since locks are held by the session, different statements in the same session cannot block each other.
Justin