Re: UUID v7

> On 12 Dec 2024, at 23:08, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> Pushed

Hi Masahiko!

I’ve found some inconsistency in handling of overflow. I’m not sure we should handle it, but anyway.

postgres=# select x,
    uuid_extract_timestamp(uuidv7((x::text || ' year'::text)::interval)),
    (x::text || ' year'::text)::interval
from generate_series(237,238) x;;
  x  |   uuid_extract_timestamp    | interval
-----+-----------------------------+-----------
 237 | 2262-01-30 13:43:23.737+05  | 237 years
 238 | 10598-02-10 19:41:13.736+05 | 238 years
(2 rows)

The thing is per RFC we represent time as number of nanoseconds since UNIX epoch. And we use int64, which will overflow
inyear 2262. I sincerely wish us to see this great year. 
We can have a couple more centuries if we resort to unsigned int 64.

But it would be great to make our code work until

postgres=# select uuid_extract_timestamp('FFFFFFFF-FFFF-7FFF-bFFF-FFFFFFFFFFFF');
   uuid_extract_timestamp
-----------------------------
 10889-08-02 10:31:50.655+05
(1 row)

And using uint64 won’t help us.


Can we use int128 in code? Or, perhaps, carry this extra 10 bits in the extra argument of generate_uuidv7()? Or,
perhaps,leave things as they stand now? 

Thanks!


Best regards, Andrey Borodin.