>>> On Tue, Oct 16, 2007 at 3:43 PM, in message
<200710162043(dot)l9GKhGeF091013(at)wwwmaster(dot)postgresql(dot)org>, "ssurui"
<ssurui(at)gmail(dot)com> wrote:
> use top command observe the available memory
top is not the best way to look at RAM usage. Try free or other tools.
> I find about 500MB memory is
> vanished after the SQL is executed.
Meaning that it is used by the OS cache? That would make sense,
given that you just read all the data pages for the table.
-Kevin