Infinite version request loop (FastAPI with SQLAlchemy hitting a Trino docker desktop container)

[jonroquet2]

Expected behavior

1. Web application starts
2. Post request to application causes a connection to local trino server
3. Connection makes a simple query (select * from tpch.sf1.nation) using sqlalchemy
4. Data rows returned and logged

Code:
`

engine = create_engine("trino://jon@localhost:8080/system")
conn = engine.connect()

result = conn.execute(text("select 1 as x")).fetchall()
for row in result:
    logger.debug(row)

`

Actual behavior

Infinite loop of code requests calling "select version()" hit the local trino server, and python goes into an infinite loop:

(Note, this is one of several thousand, this never stops)

INFO 2025-05-21 15:58:51,240 trino.client 1013 - failed after 1 attempts
DEBUG 2025-05-21 15:58:51,243 urllib3.connectionpool 241 - Starting new HTTP connection (1269): localhost:8080
DEBUG 2025-05-21 15:58:51,255 urllib3.connectionpool 544 - http://localhost:8080 "POST /v1/statement HTTP/1.1" 200 351
DEBUG 2025-05-21 15:58:51,261 urllib3.connectionpool 544 - http://localhost:8080 "GET /v1/statement/queued/20250521_205902_04901_q83nv/ya189522748922861480aa59bd1ca7af2d04dc2fc/1 HTTP/1.1" 200 351
DEBUG 2025-05-21 15:58:51,268 urllib3.connectionpool 544 - http://localhost:8080 "GET /v1/statement/queued/20250521_205902_04901_q83nv/yae1ef533103b0d4dfe33f7c45c07325f4aa00b79/2 HTTP/1.1" 200 359
DEBUG 2025-05-21 15:58:51,276 urllib3.connectionpool 544 - http://localhost:8080 "GET /v1/statement/executing/20250521_205902_04901_q83nv/y201189cbc98d1a1f97104f718b9c6372baf9e43f/0 HTTP/1.1" 200 558
DEBUG 2025-05-21 15:58:51,284 urllib3.connectionpool 544 - http://localhost:8080 "GET /v1/statement/executing/20250521_205902_04901_q83nv/ya857eae45b999e5c9ab9fa64ff14b3a9e8a736a7/1 HTTP/1.1" 200 479

Steps To Reproduce

DBMS: Run a local docker container using trinodb/trino:latest
OS: WIndows 11
Python App: Python 3.10 or 3.12 (attempted using both)
Python Libraries:
trino==0.334.0
sqlalchemy==2.0.38

Using the above code, attempt to call your local docker trino. Any query fails - it never gets to the actual query.

Log output

The issue is the select version call in dialect.py:
def _get_server_version_info(cls, connection: Connection) -> Any: def get_server_version_info(_): query = "SELECT version()" try: res = connection.execute(sql.text(query)) version = res.scalar() return tuple([version]) except exc.ProgrammingError as e: logger.debug(f"Failed to get server version: {e.orig.message}") return None

When I replace this with "return 475", all behavior is now as expected.

Operating System

Windows 11

Trino Python client version

0.334.0

Trino Server version

475

Python version

3.12.9

Are you willing to submit PR?

• Yes I am willing to submit a PR!