Postgres 14

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 select encode(uuid_send('a44521d0-0fb8-4ade-8002-3385545c3318'::uuid),'base64');

encode

pEUh0A+4St6AAjOFVFwzGA==

SELECT 1

select uuid_send('a44521d0-0fb8-4ade-8002-3385545c3318'::uuid)::bytea

uuid_send

\xa44521d00fb84ade80023385545c3318

SELECT 1

select decode('pEUh0A+4St6AAjOFVFwzGA==','base64')

decode

\xa44521d00fb84ade80023385545c3318

SELECT 1

select substring(decode('pEUh0A+4St6AAjOFVFwzGA==','base64')::text from 3)::uuid

substring

a44521d0-0fb8-4ade-8002-3385545c3318

SELECT 1

select 
    substring(decode('pEUh0A+4St6AAjOFVFwzGA==','base64')::text from 3)::uuid as classic,
    encode(uuid_send('a44521d0-0fb8-4ade-8002-3385545c3318'::uuid),'base64') as b64,
    (substring(decode('pEUh0A+4St6AAjOFVFwzGA==','base64')::text from 3)::uuid = 
        'a44521d0-0fb8-4ade-8002-3385545c3318'::uuid)::text as equals

classic
b64
equals

a44521d0-0fb8-4ade-8002-3385545c3318
pEUh0A+4St6AAjOFVFwzGA==
true

SELECT 1