In Python with sqlite is it necessary to close a cursor?

Question

Here is the scenario. In your function you're executing statements using a cursor, but one of them fails and an exception is thrown. Your program exits out of the function before closing the cursor it was working with. Will the cursor float around taking up space? Do I have to close the cursor?

Additionally, the Python documentation has an example of cursor use and says: "We can also close the cursor if we are done with it." The keyword being "can," not "must." What do they mean precisely by this?

Answer 1

You're not obliged to call close() on the cursor; it can be garbage collected like any other object.

But even if waiting for garbage collection sounds OK, I think it would be good style still to ensure that a resource such as a database cursor gets closed whether or not there is an exception.

Answer 2

It's probably a good idea (although it might not matter much with sqlite, don't know there, but it'll make your code more portable). Further, with recent Python (2.5+), it's easy:

from __future__ import with_statement
from contextlib import closing

with closing(db.cursor()) as cursor:
    # do some stuff

Answer 3

I haven't seen any effect for the sqlite3.Cursor.close() operation yet.

After closing, you can still call fetch(all|one|many) which will return the remaining results from the previous execute statement. Even running Cursor.execute() still works ...