SQL> -- create sequence g; commit;
SQL> alter sequence g restart with 0; commit;
SQL> insert into t select gen_id(g,1), 1 from rdb$types rows 5; commit;
SQL> select * from t;

          ID          F01
============ ============
           1            1
           2            1
           3            1
           4            1
           5            1

 session #1 
SQL> update t set f01=2;

 session #2 
SQL> commit; select * from mon$statements where mon$attachment_id<>current_connection;

MON$STATEMENT_ID                128
MON$ATTACHMENT_ID               57
MON$TRANSACTION_ID              <null>
MON$STATE                       0
MON$TIMESTAMP                   <null>
MON$SQL_TEXT                    0:4
 update t set f01=2 
MON$STAT_ID                     7

SQL> commit; delete from mon$statements where mon$attachment_id<>current_connection;

 session #1 
SQL> commit;
Statement failed, SQLSTATE = HY008
operation was cancelled

SQL> commit;  -- again! 
SQL> select * from t;

          ID          F01
============ ============
           1            2
           2            2
           3            2
           4            2
           5            2

commit; delete from mon$statements where ...