Re: [PATCH] Add a source for beets library databases

On Sat, 16 Dec 2023 16:54:38 -0800
Ian Eure <[email protected]> wrote:

> > If beets is built to expect other programs to access its 
> > database directly then this would work.
> >  
> 
> Beets uses SQLite, which doesn’t support concurrent access at all, 
> even read-only.  In practice, this isn’t much of a problem, 
> because beets is run infrequently, like when you want to add new 
> music.
> 
> There are workarounds, such as copying the database or hard 
> linking it, both of which defeat SQLite’s locking mechanism. 
> Though hard linking isn’t portable to non-unix-like platforms, and 
> is fairly dangerous -- defeating the locking means that if either 
> EMMS or Beets writes to the .sqlite3 file, the other accessor will 
> likely blow up.

Afaik SQLite and its python wrapper work quite well with concurrency in
its write-ahead-logging mode (added back some 10+ years ago), but it
has to be enabled via "pragma journal_mode=wal", which I don't think
beets does.

So I think it might be more of a beets code limitation at the moment.


P.S.

If you're curious about the difference, I've put up a patched-up old
script which I've used to test python wrapper and its parameters here:

  https://gist.github.com/mk-fg/bcca57313c725c6ccceeacca959ae3bf

With "-J wal" it works roughly similar to other db engines 
(which all use WAL by default of course) with any number of
concurrent reader/writer processes.

That doesn't affect how beets works ofc, unless someone changes it there.

-- 
Mike Kazantsev // fraggod.net