You should never use a truly random UUID for an indexed column like the primary key.

The clustering of the random values makes for terrible indexes, you should use something like uuid_generate_v7();

This has the added benefit of being able to get the timestamp out of the primary key e.g.

SELECT uuid_v7_to_timestamptz('018570bb-4a7d-7c7e-8df4-6d47afd8c8fc');

uuid_v7_to_timestamptz

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2023-01-02 04:26:40.637+00

The concept of system_id for marking special rows was interesting, I haven't seen it described in quite that way.