Re: making relfilenodes 56 bits

On Thu, Jun 30, 2022 at 12:41 AM Simon Riggs
<simon.riggs@enterprisedb.com> wrote:
> The reason to mention this now is that it would give more space than
> 56bit limit being suggested here.

Isn't 2^56 enough, though?  Remembering that cluster time runs out
when we've generated 2^64 bytes of WAL, if you want to run out of 56
bit relfile numbers before the end of time you'll need to find a way
to allocate them in less than 2^8 bytes of WAL.  That's technically
possible, since SMgr CREATE records are only 42 bytes long, so you
could craft some C code to do nothing but create (and leak)
relfilenodes, but real usage is always accompanied by catalogue
insertions to connect the new relfilenode to a database object,
without which they are utterly useless.  So in real life, it takes
many hundreds or typically thousands of bytes, much more than 256.