ср, 7 окт. 2020 г. в 10:51, Thorsten Schöning <tschoening@am-soft.de>:
>
> Hi all,
>
> I'm regularly reading that Postgres is often used with containers and
> in cloud environments these days, even on some not too powerful NAS.
>
> What are the lowest resource setups you know of or even host Postgres
> successfully with yourself? It's especially about RAM and CPU, if you
> needed to e.g. configure anything special to make things somewhat work
> in your stripped down environment etc.
AFAIK the default configuration of Postgres is fairly conservative and
may be a good starting point for such cases.
>
> Is there any point at which one is most likely forced to switch to
> more specialized embedded databases like SQLite? E.g. because
> Postgres requires a higher amount of resources because of it's
> architecture? Or could Postgres in theory be used everywhere where
> SQLite is used as well, as long as one is allowed to e.g. start an
> additional process?
For example, when you need to INSERT tens of thousands rows per second
on your low-cost device SQLite is a choice. Postgres is a
client-server with related overheads. Postgres requires deployment and
configuration while SQLite just works with zero-configuration (which
is a big advantage in case of IoT).
Sure, in theory Postgres can be used instead of SQLite (and vice-versa).
>
> I would like to know if there's any realistic chance to use Postgres
> in a low resources environment with little amount of RAM and somewhat
> slow CPU like the following:
>
> http://ww1.microchip.com/downloads/en/DeviceDoc/ATSAMA5D27-WLSOM1-Datasheet-60001590b.pdf
> http://ww1.microchip.com/downloads/en/DeviceDoc/SAMA5D2-Series-Data-sheet-ds60001476F.pdf
>
> One point is that I most likely need somewhat concurrent access to the
> data, because of having web services exposing that data to clients,
> daemons storing data locally only etc. OTOH, the number of concurrent
> accessed won't be too high, there won't be too much load most of the
> time. Things heavily depend on actual users of the device. Postgres'
> architecture seems to better fit that use case than e.g. SQLite.
In many cases concurrency is not a problem and in fact SQLite may
handle concurrent requests faster than Postgres. Since SQLite is
server-less and access overhead is near to zero (compared to Postgres)
each writer does its work quickly and no lock lasts for more than a
few dozen milliseconds.
On the other hand, Postgres is better in cases of really high concurrency.