Performance JOIN specified in FROM rather than WHERE

Question

Greetings,
Now that 9i can use the JOIN keyword, I was wondering if there is a performance difference between the following two approaches:
1.
from
table1 t1 join table2 t2 on t1.field1 = t2.field1
2.
from
table1 t1, table2 t2
where
t1.field1 = t2.field1
I'm new to using 9i, but in DB2 the first approach is much more efficient than the 2nd approach. I was wondering if Oracle might have similar advantages?
Many thanx for your thoughts.
Regards,
-matt

Answer 1

Lets take a look:
SQL> set autotrace traceonly
SQL> select empno
2 from emp e, dept d
3 where e.deptno=d.deptno;
14 rows selected.
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 NESTED LOOPS
2 1 TABLE ACCESS (FULL) OF 'EMP'
3 1 INDEX (UNIQUE SCAN) OF 'PK_DEPT' (UNIQUE)
Statistics
0 recursive calls
2 db block gets
4 consistent gets
0 physical reads
0 redo size
900 bytes sent via SQL*Net to client
503 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
14 rows processed
SQL> select empno
2 from emp e join dept d on e.deptno=d.deptno;
14 rows selected.
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 NESTED LOOPS
2 1 TABLE ACCESS (FULL) OF 'EMP'
3 1 INDEX (UNIQUE SCAN) OF 'PK_DEPT' (UNIQUE)
Statistics
0 recursive calls
2 db block gets
4 consistent gets
0 physical reads
0 redo size
900 bytes sent via SQL*Net to client
503 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
14 rows processed
SQL>
Execution wise and statistically these two queries are the same. Experiment with more complex joins, maybe the results will differ.