python - SQLAlchemy unstable behaviour with Oracle -

i've been trying resolve sqlalchemy issue i'm having , narrowed down simple script:

#!/usr/bin/env python  flask import flask flask.ext.sqlalchemy import sqlalchemy  app = flask(__name__) app.config["sqlalchemy_database_uri"] = "oracle+cx_oracle://<user>:<password>@<sid>"  db = sqlalchemy(app)  class instance(db.model):     id = db.column(db.integer, primary_key=true)  app.app_context():     instance = db.session.query(instance).filter(instance.id == 105250).first()     print(instance) 

the instance id 105250 indeed exists in database, results i'm getting quite surprising:

% x.py <__main__.instance object @ 0x7f65461cdef0> % x.py <__main__.instance object @ 0x7f0c09aa2ef0> % x.py none % x.py <__main__.instance object @ 0x7fd1c7a9eef0> % x.py none 

can explain how prevent , fix unstable behaviour?

i found root cause. posting here, in case runs same issue.

the problem caused unstable cx_oracle 5.2.0 driver. downgrading 5.1.3 fixed issue.