ValueError: could not convert string to float

[Trolldemorted]

Given this extremely simple example:

source_engine = create_async_engine(
    f"mysql+asyncmy://{user}:{password}@{host}:{port}/{database}?charset=utf8",
    echo=True)

handled_rows = 0
lower_bound = 1_000_000 * int(sys.argv[1])
upper_bound = 1_000_000 + lower_bound
async with source_engine.begin() as conn:
    async for row in await conn.stream(text(f"SELECT * FROM {table} WHERE {lower_bound} <= ID AND ID < {upper_bound};")):
        handled_rows += 1
        if handled_rows % 10000 == 0:
            logger.info(f"{lower_bound} - {upper_bound} handled {handled_rows}")

in a fresh venv with these dependencies:

asyncmy==0.2.5
greenlet==1.1.3.post0
SQLAlchemy==1.4.42

I sometimes get this ValueError:

2022-10-27 10:42:50,471 INFO sqlalchemy.engine.Engine ROLLBACK
2022-10-27 10:42:50,471 INFO MainThread - sqlalchemy.engine.Engine:1055 _rollback_impl -- ROLLBACK
Traceback (most recent call last):
  File "test.py", line 55, in <module>
    asyncio.run(main())
  File "/usr/local/lib/python3.8/asyncio/runners.py", line 43, in run
    return loop.run_until_complete(main)
  File "/usr/local/lib/python3.8/asyncio/base_events.py", line 608, in run_until_complete
    return future.result()
  File "test.py", line 50, in main
    async for row in await conn.stream(text(f"SELECT * FROM {table} WHERE {lower_bound} <= ID AND ID < {upper_bound};")):
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/ext/asyncio/result.py", line 174, in __anext__
    row = await greenlet_spawn(self._onerow_getter, self)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 128, in greenlet_spawn
    result = context.switch(value)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/result.py", line 457, in onerow
    row = self._fetchone_impl()
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/result.py", line 1340, in _fetchone_impl
    return self._real_result._fetchone_impl(hard_close=hard_close)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/cursor.py", line 1816, in _fetchone_impl
    return self.cursor_strategy.fetchone(self, self.cursor, hard_close)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/cursor.py", line 1096, in fetchone
    self._buffer_rows(result, dbapi_cursor)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/cursor.py", line 1068, in _buffer_rows
    self.handle_exception(result, dbapi_cursor, e)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/cursor.py", line 955, in handle_exception
    result.connection._handle_dbapi_exception(
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 2128, in _handle_dbapi_exception
    util.raise_(exc_info[1], with_traceback=exc_info[2])
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/util/compat.py", line 208, in raise_
    raise exception
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/engine/cursor.py", line 1066, in _buffer_rows
    new_rows = dbapi_cursor.fetchmany(size)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/dialects/mysql/asyncmy.py", line 169, in fetchmany
    return self.await_(self._cursor.fetchmany(size=size))
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 68, in await_only
    return current.driver.switch(awaitable)
  File "/foo/.venv2/lib/python3.8/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 121, in greenlet_spawn
    value = await result
  File "asyncmy/cursors.pyx", line 515, in fetchmany
  File "asyncmy/cursors.pyx", line 482, in read_next
  File "asyncmy/connection.pyx", line 1116, in _read_rowdata_packet_unbuffered
  File "asyncmy/connection.pyx", line 1157, in asyncmy.connection.MySQLResult._read_row_from_packet
ValueError: could not convert string to float: '751>2402'

Any clue what might be happening?

[long2ice]

Can you show the table struct and the real data in it?

[Trolldemorted]

Unfortunately not, the data is sensitive and I didn't have the time to reproduce it with dummy data