John Sales <spelunker334@yahoo.com> writes:
> By doing this, I'm hoping that the query optimizer is smart enough to see that if a query comes in and requests only
thesix columns (that are in the narrower table) that PostgreSQL won't have to load the wider table into the buffer
pool,and thereby actually have to only access about 10% the amount of disk that it presently does.
> Is this a sound theory?
No. It still has to touch the second table to confirm the existence of
rows to join to.
regards, tom lane
