Re: Is it OK to create a directory in PGDATA dir

On Thu, Oct 19, 2017 at 5:32 PM, John R Pierce <pierce(at)hogranch(dot)com> wrote:

> On 10/19/2017 1:25 PM, Tomas Vondra wrote:
>
> Is it fine to create a subdir inside PGDATA and store our stuff
> there, or will PG freak out seeing a foreign object.
>
>
> PostgreSQL certainly does not check if there are unknown directories in
> the data directory, and it will not crash and burn. But it causes all
> sorts of problems, and it increases the probability of human error.
>
>
> most importantly, ONLY the postgres system process should have access to
> the pgdata directory, it should have permissions 700. your apps should be
> running as a different user, and that user won't have access to said PGDATA.
>
Untrusted languages in the server, and superuser use of COPY, count as
"applications" that are going to be running under the postgres user as far
as the O/S is concerned.

​I do agree that external applications should communicate with the server
via a session and not by mutual knowledge of a filesystem location.

I too would recommend not conflating system-related data that belongs in
PGDATA and application-related data that should reside outside of that
location.

​
​D
​avid J.​