[database-devel] Multi-threaded access to an SQLite database

[Janne Hellsten]

Moving the discussion over to database-devel - others may find this
interesting / may have run into this.

FWIW - I also tried setting up a test case which would have multiple
concurrent writers, but couldn't get this to fail.  I suspect though
that my test case wasn't good enough to hit this problem.

Background: This originated from [1], also collected some notes on [2].

  [1]: https://github.com/nurpax/snaplet-sqlite-simple/issues/5
  [2]: here: http://nurpax.github.com/posts/2013-01-04-note-to-self.html

Janne


On Sat, Jan 5, 2013 at 12:38 AM, Joey Adams <joeyadams3.14159 at gmail.com> wrote:
> On Fri, Jan 4, 2013 at 4:43 PM, Janne Hellsten <jjhellst at gmail.com> wrote:
>>
>> I was just wondering if you have any past experience on multi-threaded
>> use of SQLite?  I hit some issues last week, started seeing
>> SQLITE_BUSY on inserts and wasn't quite sure what to think about it.
>> I wrote some notes about it here
>> http://nurpax.github.com/posts/2013-01-04-note-to-self.html.  Have you
>> by any chance had to deal with such problems before?
>
>
> According to the SQLite FAQ [1], only one writer can access the database at
> a time.  I haven't run into this myself, though.
>
> Be careful with transactions.  If you allow multiple threads to access a
> database handle, and to issue BEGIN/COMMIT on their own terms, then one
> thread might issue BEGIN and interfere with other transactions.  Thus, make
> sure the MVar lock is held for the duration of the transaction.
>
> PS: Mind CCing this to database-devel at haskell.org ?
>
>  [1]: http://www.sqlite.org/faq.html#q5