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POOperationalError "unable to open database file" processing query results with SQLAlchemy and SQLite3
 

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  1. POOperationalError "unable to open database file" processing query results with SQLAlchemy and SQLite3
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    <p>I'm running into this little problem that I hope is just a dumb user error. It looks like some sort of a size limit with a query to a SQLite database. I managed to reproduce the issue with an in-memory DB and a simple script shown below. I can make it work by either reducing the number of records in the DB; or by reducing the size of each record; or by dropping the order_by() call. I am using Python 2.5.5 and SQLAlchemy 0.6.0 in a Cygwin environment.</p> <p>Thanks!</p> <pre><code>#!/usr/bin/python from sqlalchemy.orm import sessionmaker import sqlalchemy import sqlalchemy.orm class Person(object): def __init__(self, name): self.name = name engine = sqlalchemy.create_engine('sqlite:///:memory:') Session = sessionmaker(bind=engine) metadata = sqlalchemy.schema.MetaData(bind=engine) person_table = sqlalchemy.Table('person', metadata, sqlalchemy.Column('id', sqlalchemy.types.Integer, primary_key=True), sqlalchemy.Column('name', sqlalchemy.types.String)) metadata.create_all(engine) sqlalchemy.orm.mapper(Person, person_table) session = Session() session.add_all([Person("012345678901234567890123456789012") for i in range(5000)]) session.commit() persons = session.query(Person).order_by(Person.name).all() print "count =", len(persons) session.close() </code></pre> <p>The all() call to the query result fails with the OperationalError exception:</p> <pre><code>Traceback (most recent call last): File "./stress.py", line 27, in &lt;module&gt; persons = session.query(Person).order_by(Person.name).all() File "/usr/lib/python2.5/site-packages/sqlalchemy/orm/query.py", line 1343, in all return list(self) File "/usr/lib/python2.5/site-packages/sqlalchemy/orm/query.py", line 1451, in __iter__ return self._execute_and_instances(context) File "/usr/lib/python2.5/site-packages/sqlalchemy/orm/query.py", line 1456, in _execute_and_instances mapper=self._mapper_zero_or_none()) File "/usr/lib/python2.5/site-packages/sqlalchemy/orm/session.py", line 737, in execute clause, params or {}) File "/usr/lib/python2.5/site-packages/sqlalchemy/engine/base.py", line 1109, in execute return Connection.executors[c](self, object, multiparams, params) File "/usr/lib/python2.5/site-packages/sqlalchemy/engine/base.py", line 1186, in _execute_clauseelement return self.__execute_context(context) File "/usr/lib/python2.5/site-packages/sqlalchemy/engine/base.py", line 1215, in __execute_context context.parameters[0], context=context) File "/usr/lib/python2.5/site-packages/sqlalchemy/engine/base.py", line 1284, in _cursor_execute self._handle_dbapi_exception(e, statement, parameters, cursor, context) File "/usr/lib/python2.5/site-packages/sqlalchemy/engine/base.py", line 1282, in _cursor_execute self.dialect.do_execute(cursor, statement, parameters, context=context) File "/usr/lib/python2.5/site-packages/sqlalchemy/engine/default.py", line 277, in do_execute cursor.execute(statement, parameters) sqlalchemy.exc.OperationalError: (OperationalError) unable to open database file u'SELECT person.id AS person_id, person.name AS person_name \nFROM person ORDER BY person.name' () </code></pre>
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