Bruce Momjian wrote:
> I am just writing the EXISTS section from my book. I don't think it
> matters what fields are returned from an EXISTS subquery. If I am
> wrong, someone please let me know.
Celko also writes (in his chapter on EXISTS in "SQL for Smarties"):
"In general the SELECT * option should perform better than the actual column.
It lets the query optimizer decide which column to use. If a column has an
index on it, then simply seeing a pointer to the index is enough to determine
that something exists."
Obviously you're in a much better position than me to judge whether that's the
case in pgsql! But it might be worth a test.
Julian Scarfe