Re: RAM usage of PostgreSql

Hi,

|Cc: pgsql-novice(at)postgresql(dot)org, pgsql-performance(at)postgresql(dot)org
Please don't cross post to multiple lists.

On Thu, Apr 04, 2019 at 08:18:01PM +0530, Prasad wrote:
> There are lot of allocations in postgresql.conf file, for example
> shared_buffers, work_mem...etc.
>
> As per my knowledge, all postgres processes should not consume the RAM more
> than the value assigned in shared_buffers.Please clarify and let me know if
> I misunderstand the concept..

shared_buffers is what's *reserved* for postgres and unavailable for other
processes whenever PG is running.

work_mem is what each postgres process might use, if needed. When complete,
that's returned to the OS. Note that an expensive query might actually use
some multiple of work_mem (it's per sort/hash node and also per parallel
process, and also hash aggregate can sometimes use more than work_mem).

Justin