1280 UUID v7 support

[dantownsend]

Resolves #1280

[dantownsend]

Cockroach doesn't have UUID 7 support yet (as far as I can see).

I guess we can just raise NotImplemented for now.

[dantownsend]

I'm going to split these changes out into a separate PR.

[sinisaos]

@dantownsend Just one question. How would you solve this Postgres error without having to install some uuidv7 extension. Do you have another plan?

[dantownsend]

@dantownsend Just one question. How would you solve this Postgres error without having to install some uuidv7 extension. Do you have another plan?

I was going to just put in the docs that it's Postgres 18 only for now.

I think there are some scripts out there somewhere which would allow us to use uuid 7 on older versions. If you can find one I'm not averse to using it (it might also solve the problem for CockroachDB too).

[sinisaos]

I tried this custom function and by adding this function I was able to pass the tests. I don't know if this is the correct way to use it, but I added that custom function to postgres.py like this

if current_transaction:
    await current_transaction.connection.execute(
        """
        -- Source: https://gist.github.com/kjmph/5bd772b2c2df145aa645b837da7eca74
        create or replace function uuidv7()
        returns uuid
        as $$
        begin
        -- use random v4 uuid as starting point (which has the same variant we need)
        -- then overlay timestamp
        -- then set version 7 by flipping the 2 and 1 bit in the version 4 string
        return encode(
            set_bit(
            set_bit(
                overlay(uuid_send(gen_random_uuid())
                        placing substring(int8send(floor(extract(epoch from clock_timestamp()) * 1000)::bigint) from 3)
                        from 1 for 6
                ),
                52, 1
            ),
            53, 1
            ),
            'hex')::uuid;
        end
        $$
        language plpgsql
        volatile;
        """
    )
    response = await current_transaction.connection.fetch(ddl)

I also tried those changes in the app using id = UUID(primary_key=True, default=UUID7()) and it worked. UUID7 is generated correctly.

[dantownsend]

I tried this custom function and by adding this function I was able to pass the tests. I don't know if this is the correct way to use it, but I added that custom function to postgres.py like this

if current_transaction:
    await current_transaction.connection.execute(
        """
        -- Source: https://gist.github.com/kjmph/5bd772b2c2df145aa645b837da7eca74
        create or replace function uuidv7()
        returns uuid
        as $$
        begin
        -- use random v4 uuid as starting point (which has the same variant we need)
        -- then overlay timestamp
        -- then set version 7 by flipping the 2 and 1 bit in the version 4 string
        return encode(
            set_bit(
            set_bit(
                overlay(uuid_send(gen_random_uuid())
                        placing substring(int8send(floor(extract(epoch from clock_timestamp()) * 1000)::bigint) from 3)
                        from 1 for 6
                ),
                52, 1
            ),
            53, 1
            ),
            'hex')::uuid;
        end
        $$
        language plpgsql
        volatile;
        """
    )
    response = await current_transaction.connection.fetch(ddl)

I also tried those changes in the app using id = UUID(primary_key=True, default=UUID7()) and it worked. UUID7 is generated correctly.

Thanks for this. I'm still a bit undecided how deep to go on this. Maybe we add this to the docs if people want to use UUID7 on older versions of Postgres.

[sinisaos]

Here is another example of a custom Postgres uuid v7 function (from Piccolo issues). What I like about uuid v7 is they are sequential (similar to Serial column ). Cockroach does not work with uuid v7 in my case.