why does sqlalchemy UUID succeed with mysql BINARY(16) but fails with postgres BYTEA

readme.md

Here a docker compose to test

version: '3.4'

volumes:
  pg_vol:
    driver: local
  my_vol:
    driver: local

services:
  db:
    container_name: 'pg'
    image: postgres
    restart: always
    environment:
      POSTGRES_PASSWORD: pass
      POSTGRES_ROOT_PASSWORD: pass
      POSTGRES_USER: user
      POSTGRES_DB: db
    volumes:
      - pg_vol:/var/lib/postgresql/data
    ports:
      - 5432:5432

  db2:
    container_name: 'my'
    image: mysql
    command: --default-authentication-plugin=mysql_native_password
    environment:
      MYSQL_PASSWORD: pass
      MYSQL_ROOT_PASSWORD: pass
      MYSQL_USER: user
      MYSQL_DATABASE: db
    ports:
      - 3306:3306
    volumes:
      - my_vol:/var/lib/mysql

The postgres database is populated

db=# select * from t;
                 id                 
------------------------------------
 \xfb2f42c0670711eea94d0242ac1a0002
 \xfd3b61aa670711eea94d0242ac1a0002
 \xfdaab2c7670711eea94d0242ac1a0002
 \xfe073a8d670711eea94d0242ac1a0002
 \xfe5d9ba4670711eea94d0242ac1a0002

and mysql

mysql> select * from t;
+------------------------------------+
| id                                 |
+------------------------------------+
| 0xFB2F42C0670711EEA94D0242AC1A0002 |
| 0xFD3B61AA670711EEA94D0242AC1A0002 |
| 0xFDAAB2C7670711EEA94D0242AC1A0002 |
| 0xFE073A8D670711EEA94D0242AC1A0002 |
| 0xFE5D9BA4670711EEA94D0242AC1A0002 |

Here is the python script to test

from sqlalchemy import create_engine, Column
from sqlalchemy.orm import sessionmaker, declarative_base
from sqlalchemy_utils import UUIDType
# from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy import UUID

Base = declarative_base()

class T(Base):
    __tablename__ = "t"
    id = Column(UUIDType(binary=True), primary_key=True)
  # id = Column(UUID, primary_key=True)


if __name__ == "__main__":
    engine = create_engine("postgresql://user:pass@localhost:5432/db")
    # engine = create_engine('mysql://user:pass@127.0.0.1:3306/db')
    Session = sessionmaker(bind=engine)
    session = Session()

    # Query the table and print the UUIDs
    results = session.query(T).all()
    for row in results:
        print(row.id)

Postgres

Running this with id = Column(UUIDType(binary=True), primary_key=True)

user@dell:~$ python3 scrap.py 

Traceback (most recent call last):
  File "/home/git/mysql-uuid/scrap.py", line 26, in <module>
    results = session.query(T).all()
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/orm/query.py", line 2688, in all
    return self._iter().all()  # type: ignore
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 1786, in all
    return self._allrows()
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 554, in _allrows
    rows = self._fetchall_impl()
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 1693, in _fetchall_impl
    return self._real_result._fetchall_impl()
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 2293, in _fetchall_impl
    return list(self.iterator)
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/orm/loading.py", line 191, in chunks
    fetch = cursor._raw_all_rows()
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 547, in _raw_all_rows
    return [make_row(row) for row in rows]
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 547, in <listcomp>
    return [make_row(row) for row in rows]
  File "lib/sqlalchemy/cyextension/resultproxy.pyx", line 16, in sqlalchemy.cyextension.resultproxy.BaseRow.__init__
  File "lib/sqlalchemy/cyextension/resultproxy.pyx", line 73, in sqlalchemy.cyextension.resultproxy._apply_processors
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy/sql/type_api.py", line 2153, in process
    return fixed_process_value(value, dialect)
  File "/home/.local/lib/python3.10/site-packages/sqlalchemy_utils/types/uuid.py", line 111, in process_result_value
    return uuid.UUID(value)
  File "/usr/lib/python3.10/uuid.py", line 174, in __init__
    hex = hex.replace('urn:', '').replace('uuid:', '')
AttributeError: 'memoryview' object has no attribute 'replace'

Then if i run it with id = Column(UUID, primary_key=True)

user@dell:~$ python3 scrap.py 

<memory at 0x7f40cf98ed40>
<memory at 0x7f40cf98eec0>
<memory at 0x7f40cf98ef80>
<memory at 0x7f40cf98f040>
<memory at 0x7f40cf98f100>
<memory at 0x7f40cf98f1c0>
<memory at 0x7f40cf98f280>
<memory at 0x7f40cf98f340>
<memory at 0x7f40cf98f400>
<memory at 0x7f40cf98f4c0>
<memory at 0x7f40cf98f580>
<memory at 0x7f40cf98f640>
<memory at 0x7f40cf98f700>
<memory at 0x7f40cf98f7c0>
<memory at 0x7f40cf98f880>
<memory at 0x7f40cf98f940>
<memory at 0x7f40cf98fa00>
<memory at 0x7f40cf98fac0>
<memory at 0x7f40cf98fb80>
<memory at 0x7f40cf98fc40>
<memory at 0x7f40cf98fd00>

Mysql

if you run the above with mysql, it succeeds... Im wondering why it succeeds for mysql but not for postgres.