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@tuarrep
Created April 22, 2024 18:48
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UUIDv7 polyfill
-- Based off IETF draft, https://datatracker.ietf.org/doc/draft-peabody-dispatch-new-uuid-format/
create or replace function uuid_generate_v7()
returns uuid
as $$
declare
unix_ts_ms bytea;
uuid_bytes bytea;
begin
unix_ts_ms = substring(int8send(floor(extract(epoch from clock_timestamp()) * 1000)::bigint) from 3);
-- use random v4 uuid as starting point (which has the same variant we need)
uuid_bytes = uuid_send(gen_random_uuid());
-- overlay timestamp
uuid_bytes = overlay(uuid_bytes placing unix_ts_ms from 1 for 6);
-- set version 7
uuid_bytes = set_byte(uuid_bytes, 6, (b'0111' || get_byte(uuid_bytes, 6)::bit(4))::bit(8)::int);
return encode(uuid_bytes, 'hex')::uuid;
end
$$
language plpgsql
volatile;
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