> gj=# explain select count(*) from smartarse where v is null;
>----------------------------------------------------------------
> Aggregate (cost=21.62..21.63 rows=1 width=0)
< -> Seq Scan on smartarse (cost=0.00..21.60 rows=6 width=0)
Thread question and sample was about using nested queries.
Your sample does not use nested queries but it shows (width=0) that all
columns are excluded.
So I do'nt understand how this applies to topic.
Andrus.