Re: Temporary file access API

On Mon, Apr 11, 2022 at 4:05 AM Antonin Houska <ah(at)cybertec(dot)at> wrote:
> There are't really that many kinds of files to encrypt:
>
> https://wiki.postgresql.org/wiki/Transparent_Data_Encryption#List_of_the_files_that_contain_user_data
>
> (And pg_stat/* files should be removed from the list.)

This kind of gets into some theoretical questions. Like, do we think
that it's an information leak if people can look at how many
transactions are committing and aborting in pg_xact_status? In theory
it could be, but I know it's been argued that that's too much of a
side channel. I'm not sure I believe that, but it's arguable.
Similarly, the argument that global/pg_internal.init doesn't contain
user data relies on the theory that the only table data that will make
its way into the file is for system catalogs. I guess that's not user
data *exactly* but ... are we sure that's how we want to roll here?

I really don't know how you can argue that pg_dynshmem/mmap.NNNNNNN
doesn't contain user data - surely it can.

--
Robert Haas
EDB: http://www.enterprisedb.com