Re: Potential memory usage issue

Bill Moran <wmoran@collaborativefusion.com> writes:
> In response to David Brain <dbrain@bandwidth.com>:
>> I am curious as to why 'top' gives such different output on the two
>> systems - the datasets are large and so I know I benefit from having
>> high shared_buffers and effective_cache_size settings.

> Have you done any actual queries on the new system?  PG won't use the
> shm until it needs it -- and that doesn't occur until it gets a request
> for data via a query.

More accurately, top won't consider shared mem to be part of the process
address space until it's actually touched by that process.

            regards, tom lane