[Tutor] SQLite database locked problem

[Christian Witts]

On 20/07/2010 06:48, Che M wrote:
> I'm using an SQLite3 database (with Python 2.5) and every so often the 
> application crashes or hangs because somewhere there is this error, or 
> something like it:
>
> OperationalError:  database is locked.
>
> This is probably because I am viewing and sometimes changing the 
> database through SQLite Database Browser while working on my app, and 
> occasionally the app tries to access the db when the Database Browser 
> is writing to it or something like that.
>
> I'd like to a) know how to reproduce the error (haven't seen it in a 
> while, but want to be sure  know when it may happen for users and b) 
> prevent it from being a problem in the running app.
>
> Any suggestions welcome.  Thank you,
> Che
>
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SQLite is technically thread safe, but a write operation locks the 
entire database [1]:
- Any resultset being step()'d through uses a shared read-only lock.
- Any insert/update being executed requires an exclusive write lock.

[1] http://www.sqlite.org/lockingv3.html

-- 
Kind Regards,
Christian Witts


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