Support musicbrainz fields in search and distinct

[kingosticks]

A fix for #42. My first attempt at using SQLite, hope I did the migration correctly.

This requires mopidy/mopidy#1900

[codecov]

Codecov Report

Merging #43 into master will not change coverage.
The diff coverage is 50.00%.

@@           Coverage Diff           @@
##           master      #43   +/-   ##
=======================================
  Coverage   50.39%   50.39%           
=======================================
  Files           9        9           
  Lines         764      764           
=======================================
  Hits          385      385           
  Misses        379      379           

Impacted Files	Coverage Δ
mopidy_local/schema.py	76.28% <50.00%> (ø)

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[jodal]

LGTM, but I don't have any experience with SQLite migrations either.

[tkem]

@kingosticks: I'm pretty impressed you could actually make some sense out of this mess ;-)
However, I think you should also update sql/schema.sql, too, for fresh installs.
AFAICS, only sql/upgrade-v6.sql has been changed. So with a fresh install, the v5 schema will be created with schema.sql, and then the upgrade-v6.sql script will be run. I always thought it would be more clear if schema.sql contains the current schema. Just easier by looking at a single file to see what's going on.
But it's debatable, since that means some code duplication in the upgrade scripts.

[tkem]

Generally looks fine, but I'd also suggest updating schema.sql accordingly.

[tkem]

BTW, since v5 was the first sqlite schema version used in mopidy-local, the older upgrade scripts could probably be dropped. I guess I should have done this when merging mopidy-local-sqlite in the first place, and maybe reset the schema version to v1.

[kingosticks]

Ahh, I didn't notice that sql/schema.sql actually matched the latest schema (the version number should have been a giveaway). That all makes sense. I've also made those suggested changes.