Choosing the best query

Question

Hi there,
Can some one help me on selecting the best query from the following two queries:
QUERY 1:
select p.name, d.descr
from table1 p, table2 d
where p.cod_table1 = d.cod_table2(+) and d.dom(+) ='T';
ID Query Plan
0 SELECT STATEMENT Cost = 5
1 HASH JOIN OUTER
2 TABLE ACCESS FULL table1
3 TABLE ACCESS BY INDEX ROWID table2
4 INDEX RANGE SCAN DDOM_DOM_FK                     
QUERY 2:
select p.name, (select d.descr from table2 d where p.cod_table1 = d.cod_table2 and d.dom='T') as descr
from table1 p;
ID Query Plan
0 SELECT STATEMENT Cost = 2
1 TABLE ACCESS FULL table1                    
I'm a bit surprise about the explain result of the second query, because there is no reference to table2 access. What's happening ?
Tks in advance for any tip,
Helena.

Answer 1

I've noticed that issue with the query plan for those types of querys (in 8.1.7. It may be better in a lter database).
I think the queries will take the same time.
However if you are basing a view on the query, the second would be better as the lookup table will only be accessed if the descr is selected from the view, and performance will therefore be better for queries not accessing the descr column.
[I asked pretty much the same question on asktom.oracle.com]