Hi All,
I have a question on the SELECT Statement where it involve the group by clause.

Example :
SELECT A.something,B.someotherthing
FROM table A, table B
WHERE B.date <= :date
GROUP BY A.something;

In this case, is the SQL statement needs indexes for the A.something.
After SQL selected out all the records which B.date <= :date into temporary space in memory, say may be 1 million records after that, does it means it will require perform full table scan in order to group the A.something ? or What is the best way to optimise the sql statement for the above scenario ?

Thanks