Need feedback on how to tune that procedure

Question

I have this procedure:
PROCEDURE need_a_tune IS
CURSOR c_tran IS
SELECT c1,c2,c3
FROM t1
WHERE c1 <= sysdate -7 FOR UPDATE;
BEGIN
FOR v_tran IN c_tran LOOP
BEGIN
INSERT INTO t2@another database (c1,c2,c3)
VALUES (v_tran.c1, v_tran.c2, v_tran.c3);
DELETE FROM t1 WHERE CURRENT OF c_tran;
END LOOP;
COMMIT;
END need_a_tune;
That procedure transfer data from database a to database b, then purge the table t1 in database a.
The cursor returns about 5millions rows. That procedure runs for about 2 hours.
I want to change this slow serial process to a fast batch process.
The guy who wrote that procedure is of course not here anymore. And i have no clue why he lock the table in the cursor. Since right after the transfer is completed, he delete the row in t1. So why the lock? Even if he lock then release the lock after the transfer, the rows are not there anymore, so no update/delete on t1 for those row anyway.
1) is it possible to change this code so it is done in sql rather than in pl/sql?
2) if not, how do i change this to a forall statement?

Answer 1

nice idea, but you can't use returning into with
insert as select:
SQL> select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bi
PL/SQL Release 10.2.0.1.0 - Production
CORE    10.2.0.1.0      Production
TNS for Linux: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
SQL> create table exm(id primary key) as select object_id from all_objects
  2  where rownum <=100;
Table created.
SQL> declare
  2  type num_tbl is table of number;
  3   ll_num_tbl num_tbl;
  4   begin
  5   insert into exm(id)
  6  (select object_id * 100 from all_objects where rownum
  7   <=100) returning id into ll_num_tbl;
  8  end;
  9  /
<=100) returning id into ll_num_tbl;
ERROR at line 7:
ORA-06550: line 7, column 9:
PL/SQL: ORA-00933: SQL command not properly ended
ORA-06550: line 5, column 2:
PL/SQL: SQL Statement ignoredAmiel