Tuning: PLSQL/INSERT INTO statement

I have a select query that I execute and it takes several minutes to get the results back. Now I want to put those results into a table so I do: INSERT INTO <TABLE>

       SELECT Query.
Now the process takes hours to complete. The table has no constraints or triggers. I did notice the temp table space keeps getting filled when I run the query with the INSERT INTO clause but not when I run just the SELECT statement. WHY?

The query looke something like this:
SELECT A1,

                  A2,
                  A3,
                  A4,
                  A5,
 FROM ( SELECT A1
                                 A2
                                 A3
                                 sum(A4)
                 FROM ( SELECT A1,
                                                 A2,
                                                 min(A3)
                                 FROM table A, Table B
                                 WHERE A1 = B1 and
                                                 A2 = B2
                                 GROUP BY A1,A2) A , TABLE B
                 WHERE A1 = B1 and
                                 A2 = B2
                  GROUP BY A1,A2,A3) AA
WHERE AA.A1 = VALUE
                AA.A2 = VALUE

Any help would be appreciated. I just don't understand why it would take any more Temp table space do the insert on this query as it would to just execute the SELECT statement alone.

• Kevin Burton