Function for generating Time Sortable ID with microsecond precision on PostgreSQL

fn_tsid_micro.sql

/**
 * Returns a Time Sortable ID with microsecond precision.
 * 
 * Time component: 52 bits (2^52 = ~71 years)
 * 
 * Random component: 12 bits (2^12 = 4,096)
 * 
 * The time component is the count of microseconds since 2020-01-01T00:00:00Z.
 *
 * Tags: tsid ulid snowflake id-generator generator time sortable sort order id
 */
create or replace function public.fn_tsid_micro() returns bigint as $$
declare
    -- Microseconds precision
    C_MICRO_PREC bigint := 10^6;
    -- Random component bit length: 12 bits
    C_RANDOM_LEN bigint := 2^12;
    -- TSID epoch: seconds since 2020-01-01Z
    -- extract(epoch from '2020-01-01'::date)
    C_TSID_EPOCH bigint := 1577836800;
begin
    return ((floor((extract('epoch' from clock_timestamp()) - C_TSID_EPOCH) * C_MICRO_PREC) * C_RANDOM_LEN)::bigint) + (floor(random() * C_RANDOM_LEN)::bigint);
end $$ language plpgsql;

-- EXAMPLE 1:
-- select fn_tsid_micro();

-- EXAMPLE 1 OUTPUT:
-- 51692546711091432