I am doing something like this...
conn = sqlite3.connect(db_filename) with conn: cur = conn.cursor() cur.execute( ... )
with
automatically commits the changes. But the docs say nothing about closing the connection.
Actually I can use conn
in later statements (which I have tested). Hence it seems that the context manager is not closing the connection.
Do I have to manually close the connection. What if I leave it open?
EDIT
My findings:
__exit__
, the context manager only commits the changes by doing conn.commit()
with conn
and with sqlite3.connect(db_filename) as conn
are same, so using either will still keep the connection alivewith
statement does not create a new scope, hence all the variables created inside the suite of with will be accessible outside itConnections are automatically closed when they are deleted (typically when they go out of scope) so you should not normally need to call [ conn. close() ], but you can explicitly close the connection if you wish. and similarly for cursors (my emphasis):
If you do not close your database connections, many problems can occur like web pages hanging, slow page loads, and more. Think of it as going through a door to your house. Maybe the door will shut by itself, but maybe it won't. If it doesn't shut, who knows what will happen.
For the purpose of safe coding, you should always close database connections explicitly to make sure that the code was able to close itself gracefully and to prevent any other objects from reusing the same connection after you are done with it.
close( conn ) closes the SQLite connection by using the MATLAB® interface to SQLite. The SQLite connection object remains open until you close it using the close function. Always close this object when you finish using it.
In answer to the specific question of what happens if you do not close a SQLite database, the answer is quite simple and applies to using SQLite in any programming language. When the connection is closed explicitly by code or implicitly by program exit then any outstanding transaction is rolled back. (The rollback is actually done by the next program to open the database.) If there is no outstanding transaction open then nothing happens.
This means you do not need to worry too much about always closing the database before process exit, and that you should pay attention to transactions making sure to start them and commit at appropriate points.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With