Which is more (faster) performance oriented? Collections or Cursor For Loop

Question

Hi,
Please help me regarding a dilemma.
Is, using a Cursor For Loop faster than a loop run upon a collection variable that was being populated using bulk collect? Why?
Thanks in advance
rollerz

Answer 1

You can just test it by yourself. Can’t you? Ok I was bit curious to know myself so I did this…
TEST ROUND 1
SQL> declare
  2     ltime integer;
  3  begin
  4     ltime := dbms_utility.get_time;
  5
  6     for i in (select level from dual connect by level <= 100000)
  7     loop
  8             null;
  9     end loop;
10
11     ltime := dbms_utility.get_time - ltime;
12     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
13  end;
14  /
ExecTime:.19 seconds...
PL/SQL procedure successfully completed.
SQL> declare
  2     ltime integer;
  3     type my_type is table of integer;
  4     lType my_type;
  5  begin
  6     ltime := dbms_utility.get_time;
  7     select level bulk collect into lType from dual connect by level <= 100000;
  8
  9     for i in 1..lType.count
10     loop
11             null;
12     end loop;
13
14     ltime := dbms_utility.get_time - ltime;
15     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
16  end;
17  /
ExecTime:.14 seconds...
PL/SQL procedure successfully completed.
TEST ROUND 2
SQL> declare
  2     ltime integer;
  3  begin
  4     ltime := dbms_utility.get_time;
  5
  6     for i in (select level from dual connect by level <= 100000)
  7     loop
  8             null;
  9     end loop;
10
11     ltime := dbms_utility.get_time - ltime;
12     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
13  end;
14  /
ExecTime:.17 seconds...
PL/SQL procedure successfully completed.
SQL> declare
  2     ltime integer;
  3     type my_type is table of integer;
  4     lType my_type;
  5  begin
  6     ltime := dbms_utility.get_time;
  7     select level bulk collect into lType from dual connect by level <= 100000;
  8
  9     for i in 1..lType.count
10     loop
11             null;
12     end loop;
13
14     ltime := dbms_utility.get_time - ltime;
15     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
16  end;
17  /
ExecTime:.13 seconds...
TEST ROUND 3
PL/SQL procedure successfully completed.
SQL> declare
  2     ltime integer;
  3  begin
  4     ltime := dbms_utility.get_time;
  5
  6     for i in (select level from dual connect by level <= 100000)
  7     loop
  8             null;
  9     end loop;
10
11     ltime := dbms_utility.get_time - ltime;
12     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
13  end;
14  /
ExecTime:.16 seconds...
PL/SQL procedure successfully completed.
SQL> declare
  2     ltime integer;
  3     type my_type is table of integer;
  4     lType my_type;
  5  begin
  6     ltime := dbms_utility.get_time;
  7     select level bulk collect into lType from dual connect by level <= 100000;
  8
  9     for i in 1..lType.count
10     loop
11             null;
12     end loop;
13
14     ltime := dbms_utility.get_time - ltime;
15     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
16  end;
17  /
ExecTime:.13 seconds...
TEST ROUND 4
PL/SQL procedure successfully completed.
SQL> declare
  2     ltime integer;
  3  begin
  4     ltime := dbms_utility.get_time;
  5
  6     for i in (select level from dual connect by level <= 100000)
  7     loop
  8             null;
  9     end loop;
10
11     ltime := dbms_utility.get_time - ltime;
12     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
13  end;
14  /
ExecTime:.16 seconds...
PL/SQL procedure successfully completed.
SQL> declare
  2     ltime integer;
  3     type my_type is table of integer;
  4     lType my_type;
  5  begin
  6     ltime := dbms_utility.get_time;
  7     select level bulk collect into lType from dual connect by level <= 100000;
  8
  9     for i in 1..lType.count
10     loop
11             null;
12     end loop;
13
14     ltime := dbms_utility.get_time - ltime;
15     dbms_output.put_line('ExecTime:'||ltime/100||' seconds...');
16  end;
17  /
ExecTime:.13 seconds...
PL/SQL procedure successfully completed.So bulk collect looks faster...
Thanks,
Karthick.