Very slow if reference cursor value in another query

Question

I have a script like below:
declare
CURSOR c1 IS
select rptd_by, total from (select rptd_by, count(rptd_by) total from LOCBUG_ALL_M group by rptd_by order by count(rptd_by) desc) where rownum < 2;
begin
FOR item IN c1 LOOP
select count(*) into bug_num from locbug_all_m h, v_nbtbug b where (h.rptd_by like item.rptd_by) and (b.nls_related=7) and (h.rptno=b.bugdb_num);
-- 6 more similar query
END LOOP;
end;
It takes nearly 4 minutes to run.
If in the loop, I change the item.rptd_by to a static value, it only takes less than 5 seconds.
The query used for cursor only takes 0.02 second to run.
Why there's such difference? How can I solve this problem? I'm running this script in HTMLDB and it could timeout if it takes minutes to run.

Answer 1

What are you really trying to select in the loop?
SQL> select * from locbug_all_m;
RPTD_BY          COL2
X1                  1
X2                  2
X3                  3
X4                  4
X5                  5
X6                  6
X7                  7
X8                  8
X9                  9
X10                10
X                  11
11 rows selected.
SQL> ed
Wrote file afiedt.buf
  1  select count(*) from locbug_all_m
  2* where rptd_by like 'X'
SQL> /
  COUNT(*)
         1
SQL> ed
Wrote file afiedt.buf
  1  select count(*) from locbug_all_m
  2* where rptd_by like 'X%'
SQL> /
  COUNT(*)
        11
SQL> select count(*) from locbug_all_m
  2  where rptd_by = 'X';
  COUNT(*)
         1