Protect against timestamp underflow in uuidv7(interval)
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You can run a PostgreSQL built from this patch straight from Docker, with no checkout and no build:
docker run --rm -p 5432:5432 ghcr.io/hackorum-dev/postgres-patch:t248620psql -h localhost -U postgresBuilt from patchset v1 (message #1), July 29, 2026 at 12:08 AM.
Every patchset is also pushed to a branch of our PostgreSQL fork, so you can check out the same tree CI built. Without a PostgreSQL checkout:
git clone --branch t248620_1 https://github.com/hackorum-dev/postgres.gitIn a checkout you already have, add the fork once:
git remote add hackorum https://github.com/hackorum-dev/postgres.gitthen, for this patchset and every later one:
git fetch hackorum t248620_1 && git checkout t248620_1Patchset v1 (message #1) is on t248620_1
We were silently allowing underflowing the generated timestamp for the
UUIDv7 value:
# SELECT uuid_extract_timestamp(uuidv7('-57 years'::interval));
uuid_extract_timestamp
-----------------------------
10889-01-23 04:02:36.375+00
(1 row)
RFC 9562[0]https://www.rfc-editor.org/rfc/rfc9562.html doesn't seem to specify that this should be allowed, so
generate an error and forbid the underflow.
I checked the Rust uuid crate[1]https://github.com/uuid-rs/uuid/blob/1e6a9669e30d53bae50fd52f16b7a1961fda236b/src/timestamp.rs#L198-L220, and it also errors out with
a timestamp earlier than the Unix epoch.
[0]: https://www.rfc-editor.org/rfc/rfc9562.html
[1]: https://github.com/uuid-rs/uuid/blob/1e6a9669e30d53bae50fd52f16b7a1961fda236b/src/timestamp.rs#L198-L220
--
Tristan Partin
PostgreSQL Contributors Team
AWS (https://aws.amazon.com)
On Tue, Jun 23, 2026 at 6:39 PM Tristan Partin <tristan@partin.io> wrote:
We were silently allowing underflowing the generated timestamp for the
UUIDv7 value:# SELECT uuid_extract_timestamp(uuidv7('-57 years'::interval));
uuid_extract_timestamp
-----------------------------
10889-01-23 04:02:36.375+00
(1 row)
Thank you, Tristan.
This has been reported and is being discussed here [1]/messages/by-id/CA+fm-RN4eMEr2tzZU_mAV-=WfdmPXJ4Ea_GpmSS8=yStSy8onQ@mail.gmail.com
[1]: /messages/by-id/CA+fm-RN4eMEr2tzZU_mAV-=WfdmPXJ4Ea_GpmSS8=yStSy8onQ@mail.gmail.com
/messages/by-id/CA+fm-RN4eMEr2tzZU_mAV-=WfdmPXJ4Ea_GpmSS8=yStSy8onQ@mail.gmail.com
Thanks,
Baji Shaik.