Postgres x509 tls certs

https://dba.stackexchange.com/questions/36416/what-is-the-best-way-to-store-x509-certificate-in-postgresql-database

CREATE OR REPLACE FUNCTION issuer(x509table) returns text 
LANGUAGE SQL IMMUTABLE AS $$
    select issuer_cn FROM extract_x509info($1.x509data);
$$;

This can then be found by

SELECT x.issuer FROM x509table x;  --works