But filesystem encryption still means that validly logged-in users see the unencrypted data. That's great for a laptop that might get stolen, or for drives that are discarded without being wiped, but are no protection against hackers who want to exfiltrate your data.
I stand by my recommendation. If someone is logged in and has access to your data directory (e.g. is root or postgres user), then they also have the TDE key or some easy way to bypass it.
TDE was added to SQL Server, with (to us, at least) minimally-noticed overhead. Oracle has it, too, but I don't know the details. The bottom line is that requirements for TDE are escalating, whether you like it or not
I'm not arguing against putting TDE in Postgres - indeed, I am all for that. But it's a very tricky thing to do technically, with minimal benefits other than "checking the box" of some security requirements document.
The bottom line is that requirements for TDE are escalating, whether you like it or not, as Yet Another Layer Of Defense against hackers exfiltrating data, and then threatening to leak it to the public.
I'd love to see a real-world example where TDE would have saved someone but disk encryption could not.
