Add file-based library persistence

[geoah]

Currently we have user library using rethinkdb which is a bit limiting as it requires users to have rethink installed or user docker.

We could really use some form of file-based nosql library that will allow the users to not have to install any external dbs. eg, tiedot

[alexmreis]

SQLite?

[geoah]

Hm. I was about to say that the main issue of using SQLite is the structure and query complexity. But...

We only need persistence for the user library for which we don't actually store the whole structure any more.

@alexmreis I think you are on to something.

Tables

Shows

• id
• title

Seasons

• show_id
• number

Episodes

• show_id
• season
• episode
• title

Files

• show_id
• season
• episode
• name
• path
• infohash
• resolution
• source
• video_codec
• audio_codec
• release_group
• crc32
• status
• retry_time

Queries

Some functionality of the user library might require additional queries but that should be an issue as scaling in a single-user client isn't really a concern.

@superdecimal should we switch to a relational db maybe?

[superdecimal]

@geoah What would be the advantages besides me not being able to find a decent embeddable nosql db?

[geoah]

@superdecimal apparently there is no such thing in golang.